How To Make A Mold For Soft Plastic Lures

Creating soft plastic lure molds transforms the way anglers approach fishing, offering complete control over bait design, color, and action. The process combines craftsmanship with practical fishing knowledge, allowing you to replicate discontinued favorites or design entirely new patterns that match specific water conditions and target species.

Understanding Soft Plastic Lure Molds

What Makes These Molds Different

Soft plastic lure molds serve as reusable templates for casting flexible fishing baits that mimic natural prey movements. Unlike hard bait molds, these require materials that can withstand repeated thermal cycling while maintaining precise detail—every ridge, tail curve, and body contour influences how fish respond to your lure.

The mold material you select determines both the quality of your lures and the longevity of your investment. Three primary options dominate the market: silicone rubber for flexibility and detail capture, aluminum for durability and production volume, and urethane for balanced performance.

Why Anglers Are Making Their Own

The economics speak clearly. A single bag of commercial soft plastics costs $5-$8, while $60 in basic materials produces hundreds of custom lures. Beyond cost savings, you gain the freedom to experiment with color combinations, scent additives, and body shapes that commercial manufacturers don’t offer.

When your favorite bait gets discontinued—like the Wave Worms Tiki Toad that some anglers still mourn—having a mold means you never run out. That security alone drives many lure makers to their first mold project.

Essential Materials and Equipment

Mold-Making Materials Comparison

Core Supplies You’ll Need

The foundation of any mold-making operation requires specific tools and materials:

• Plastisol: The primary casting material, a PVC suspension that transforms from liquid to rubber-like solid when heated to 350°F-380°F
• Mold box materials: Foam board, LEGO bricks, or plastic containers to contain the liquid mold material during curing
• Release agents: Petroleum jelly, worm oil, or specialized mold release spray prevents sticking
• Mixing containers: Heat-resistant glass measuring cups (never plastic, which warps and releases harmful chemicals)
• Temperature monitoring: Infrared thermometer to maintain precise 325°F-350°F plastisol temperatures

Safety Equipment (Non-Negotiable)

Working with heated plastisol demands respect like a blacksmith respects hot iron:

• Approved respirator: Plastisol releases fumes during heating that shouldn’t enter your lungs
• Safety goggles: Protection against hot material splashes
• Heat-resistant gloves: Leather or specialized heat gloves prevent severe burns
• Long sleeves and closed-toe shoes: Additional barrier against accidental contact with 350°F+ material

Creating Your Mold: Step-by-Step Process

Designing and Preparing Your Master

Every mold begins with a master model—the original lure you’re replicating or a custom design you’ve created. This master dictates everything about your final product, so invest time here.

Clean the master thoroughly with soap and water, removing all dirt, oils, and debris. Even microscopic contamination transfers to your mold surface and affects release properties. For carved wooden masters, sand smooth and seal with thin coats of varnish to eliminate porosity.

Consider the parting line—where two mold halves meet—during master preparation. Position this seam along the widest part of the lure body to minimize visible marks on finished baits and simplify demolding.

Building the Mold Box

Your mold box functions as a temporary container while liquid silicone or plaster cures around your master. Several approaches work equally well:

Foam board construction: Cut pieces to create walls slightly larger than your master (leaving 1/2 inch clearance on all sides), then seal joints with hot glue. Line the interior with aluminum foil sprayed with cooking spray for easier release.

LEGO brick method: Build walls using interlocking bricks on a flat baseplate, creating a watertight enclosure. This approach allows infinite size adjustments and complete reusability.

Plastic container approach: Use existing food containers as ready-made mold boxes, though you sacrifice size customization.

Prop the box at a 5-10 degree angle by placing foam underneath one end. This tilt encourages air bubbles to float away from the master toward the surface during pouring, reducing defects.

Securing the Master Inside

Position your master in the mold box center using modeling clay strips as adhesive anchors. The master should sit approximately 1/4 inch from the bottom and sides, ensuring adequate mold wall thickness.

Double-check that the master’s face points directly upward for proper symmetry. Run a bead of clay around the base where it contacts the box floor, sealing any gaps that would allow silicone to seep underneath.

For lures requiring two-part molds, embed alignment pins (small nails or brass rods) in the first half before pouring the second. These ensure perfect registration when the halves close during casting.

Mixing and Pouring Silicone Rubber

Platinum-cure silicone offers the best balance of detail capture and durability for most anglers. Follow manufacturer mixing ratios precisely—typically 1:1 or 10:1 by weight depending on the product.

Mix thoroughly for 2-3 minutes, scraping container sides and bottom to fully incorporate both components. Poor mixing leaves soft spots that cure improperly and fail prematurely.

Pour the silicone gradually in a thin stream, allowing it to flow naturally over the master without trapping air. Tilt and rotate the box to coat all surfaces evenly, aiming for approximately 1/2 inch coverage above the master’s highest point.

Most silicones cure in 4-24 hours at room temperature. Resist the temptation to demold early; incomplete curing produces tacky surfaces that tear easily.

Demolding and Finishing

Once fully cured, excess silicone peels away from the outer frame edges. Slowly work the flexible mold containing the embedded master free from the box sides, using a hobby knife to carefully separate stubborn corners.

With the silicone mold removed, gently pry or cut the master model free. This exposes the completed interior cavity, ready for casting. If the mold sticks excessively to the master, apply a thin PVA release agent next time for easier separation.

Create a pour spout by cutting a channel from the mold top into the cavity. Add small vent channels at the cavity’s far end to allow trapped air to escape during plastic injection. These design features dramatically reduce air pockets and incomplete fills.

Casting Soft Plastic Lures

Preparing and Heating Plastisol

Measure the required plastisol volume into a heat-resistant glass cup. Microwave in 1.5-2 minute intervals, stirring between each cycle to ensure even heating. The plastisol transitions from milky white to clear as it approaches proper temperature.

Monitor temperature carefully with an infrared thermometer—the target range sits between 325°F and 380°F. This narrow window represents the difference between perfectly fused plastic and either weak, tacky lures (underheated) or burned, discolored material releasing toxic fumes (overheated).

Think of plastisol like cooking an egg: there’s a precise moment between raw and scorched where everything works perfectly. Temperature control separates professional-quality lures from amateur attempts.

Adding Color, Glitter, and Scent

Once heated to proper temperature, incorporate your chosen pigments by stirring thoroughly for even color distribution. Most liquid pigments require 10-20 drops per cup of plastisol, though testing determines exact ratios for your desired shade.

Add glitter flakes sparingly—a little creates attractive shimmer while too much dulls the lure’s action. Fine glitter suspends better in hot plastisol than large flakes, which settle quickly.

Scent additives mixed into the plastisol before pouring create baits with built-in attractant. Garlic, anise, and shad scents remain popular choices, though experimentation often yields surprising results.

Pouring Technique for Bubble-Free Results

Brush a light coat of worm oil into the mold cavities as a release agent. This step ensures clean extraction without tearing delicate features like thin tails or appendages.

Pour the hot plastisol starting from one end (typically the head) and work steadily toward the tail. This direction pushes air ahead of the plastic flow rather than trapping it, minimizing bubbles.

For multi-color layered effects, pour the first color and wait approximately 30 seconds before adding the second. This timing prevents complete blending while allowing sufficient bonding between layers.

Slightly overfill the mold to account for plastic shrinkage as it cools. The excess trims away easily once cured, and underfilled molds produce incomplete lures that require scrapping.

Cooling and Demolding

Allow lures to cool in the mold for 10-15 minutes before attempting removal. Premature demolding risks tearing or permanent deformation as the plastisol hasn’t achieved full structural integrity.

Gently flex the silicone mold away from the lure edges, progressively working around the perimeter. The lure should release smoothly thanks to the worm oil preparation; stubborn spots indicate either insufficient release agent or incomplete cooling.

Trim excess plastic from the parting line and pour spout using sharp scissors or a hobby knife. Place the lure flat against your work surface during trimming for consistent results.

Advanced Customization Techniques

Creating Two-Part Injection Molds

Injection molds produce lures with finished surfaces on all sides rather than one flat edge from open-pour casting. These require building both top and bottom halves with a connecting injection port and alignment system.

The process demands precision—mold halves must close with perfect registration to avoid flash (excess plastic squeezing out) or misalignment creating off-center lures. Machined aluminum excels for injection molds due to its rigidity and ability to withstand clamping pressure.

Capsule Pour and Layering Methods

Heated aluminum molds enable capsule pouring, where you inject plastic, then immediately add a second color before the first fully cools. The heat in the aluminum helps colors meld seamlessly at their interface while maintaining distinct zones.

This technique creates realistic baitfish patterns with light bellies and dark backs, or transparent bodies with opaque cores. The finish quality exceeds open-pour layering thanks to aluminum’s ability to maintain consistent heat distribution.

Salt, Sand, and Texture Additives

Mixing fine salt into plastisol before pouring increases lure density for faster sinking rates. The salt also creates tiny texture irregularities that some anglers believe enhance strike triggers.

Sand or coffee grounds produce rough-texture baits that displace more water and provide tactile feedback when fish mouth the lure. These additives require experimentation—too much compromises structural integrity while too little provides negligible effect.

Troubleshooting Common Mold Issues

Air Bubbles in Finished Lures

Bubbles typically result from pouring too quickly, trapping air between the plastic and mold surface. Slow, steady pouring from a consistent height minimizes turbulence.

Inadequate vent channels also cause bubbles by preventing air escape as plastic fills the cavity. Add small cuts at the mold’s far end, opposite the pour spout, to provide an air exit path.

Mold Sticking and Tearing

Insufficient release agent causes sticking, as does attempting to demold before the lure fully cools. Always apply a fresh coat of worm oil or petroleum jelly before each pour, and wait the full recommended cooling time.

Silicone mold degradation after 25-100 uses reduces release properties. When sticking becomes consistent despite proper release agent application, the mold has likely reached its service life and requires replacement.

Color Separation or Bleeding

Layered colors bleed together when you add the second color too quickly after the first. Waiting 30-45 seconds allows a skin to form on the first layer’s surface, creating a natural barrier.

Incompatible pigments sometimes react chemically, causing unexpected color shifts or bleeding. Test new pigment combinations in small batches before committing to full production runs.

Cost Analysis and Production Planning

Initial Investment Breakdown

Compare this $0.50-$1.00 per lure production cost to $0.15-$0.30 per commercial soft plastic in bulk bags. The custom capability and discontinued pattern replication justify the premium for most dedicated anglers.

Production Capacity by Mold Type

Silicone molds produce 25-100 quality lures before detail degradation becomes noticeable. Budget-conscious makers often create multiple molds from a single master, rotating between them to extend effective service life.

Aluminum molds deliver 1,000+ lures with minimal wear, making them economical for popular patterns you’ll cast repeatedly. The higher upfront cost ($80-$300+) amortizes quickly when producing 50+ lures monthly.

Safety Considerations and Best Practices

Managing Plastisol Hazards

Hot plastisol at 350°F+ causes severe burns on contact—as serious as touching a hot stovetop. Always work in a well-ventilated area, preferably outdoors or near an open window with a fan exhausting fumes away from your work position.

Never lean directly over heating plastisol, as trapped air pockets occasionally cause violent bubbling and splattering. Position yourself to the side and wear full protective equipment during every pour, no exceptions.

Proper Ventilation Requirements

Plastisol fumes contain volatile organic compounds that irritate lungs and mucous membranes. An approved respirator with organic vapor cartridges provides essential protection—simple dust masks offer zero defense against these chemical vapors.

Dedicate a workspace specifically for lure making where fumes won’t affect family members or pets. Basements, garages, and outdoor covered areas work well; avoid bedrooms, kitchens, or other living spaces regardless of ventilation.

Storage and Disposal

Store liquid plastisol in sealed containers away from heat sources and direct sunlight. The material remains stable for years when properly stored but degrades rapidly once exposed to sustained temperatures above 90°F.

Dispose of hardened plastisol scraps and failed lures in regular trash—the cured material is inert and non-hazardous. Never pour liquid plastisol down drains; it solidifies in pipes and creates expensive plumbing problems.

Benefits of DIY Lure Mold Making

Complete Design Control

Adjust body length, tail thickness, appendage count, and profile contours to match specific fishing scenarios. Tournament anglers particularly value this ability to fine-tune lure characteristics based on seasonal patterns and local forage species.

Regional baitfish vary dramatically—a swimbait designed for Lake Michigan alewives needs different proportions than one mimicking Florida shiners. Creating custom molds lets you match the hatch precisely rather than approximating with commercial offerings.

Economic Advantages

After the initial $155-$285 investment, each lure costs $0.50-$1.00 in materials. An angler using 30 soft plastics per outing saves $5-$7 per trip compared to buying replacements.

Tournament competitors who lose dozens of baits during practice and competition days recoup their mold-making investment in a single season. Recreational anglers see returns over 1-2 years of regular fishing.

Preserving Discontinued Patterns

When manufacturers discontinue effective patterns, anglers face two choices: hoard remaining inventory at inflated prices or find alternatives that never quite match the original. A quality mold preserves that proven design indefinitely, immune to market forces and corporate decisions.

The Wave Worms Tiki Toad, Zoom Centipede in certain colors, and various regional soft plastics have all vanished from catalogs despite dedicated followings. Mold makers simply replicate their favorites and continue fishing with confidence.

Key Takeaways

• Platinum-cure silicone molds deliver excellent detail capture and last 25-100 uses, making them ideal for beginners and custom one-off designs
• Maintain plastisol temperature between 325°F-380°F for proper fusion—overheating releases toxic fumes while underheating creates weak, tacky lures
• Initial investment of $155-$285 produces 200+ custom lures at $0.50-$1.00 each, offering significant savings for active anglers
• Always use approved respirators, safety goggles, and heat-resistant gloves when working with hot plastisol—burns and fume exposure pose serious health risks
• Aluminum molds cost more upfront ($80-$300+) but deliver 1,000+ high-quality lures, making them economical for frequently-used patterns

Frequently Asked Questions (FAQ)

What materials work best for making soft plastic lure molds?

Platinum-cure silicone rubber ranks as the best all-around choice for soft plastic lure molds, offering excellent detail reproduction, flexibility for easy demolding, and durability for 25-100 uses. For higher production volumes, CNC-machined aluminum molds provide superior longevity with 1,000+ lure capacity, though they require significantly higher initial investment and machining capability. Beginners should start with silicone due to lower cost and simpler fabrication process.

How hot should plastisol be when pouring into molds?

Plastisol requires heating to 325°F-380°F (163°C-193°C) for proper gelation and fusion into a solid, flexible lure. Temperature control proves critical—underheated plastisol below 325°F produces weak, tacky baits that tear easily, while overheated material above 380°F burns, discolors, and releases dangerous toxic fumes. Use an infrared thermometer to monitor temperature precisely rather than estimating by appearance alone.

Can I make two-color layered soft plastic lures in homemade molds?

Two-color layered effects work excellently in homemade molds by pouring the first color, waiting 30-45 seconds for a skin to form on the surface, then adding the second color on top. This timing prevents complete color bleeding while ensuring the layers bond together permanently. Aluminum molds heated during the process enable more sophisticated capsule-pour techniques where colors meld seamlessly at their interface while maintaining distinct zones.

How many lures can I make from one silicone mold before it wears out?

Silicone molds typically produce 25-100 high-quality lures before detail degradation becomes noticeable, depending on the mold’s complexity, plastisol temperature during pouring, and demolding care. Simpler designs with minimal undercuts last longer than intricate patterns with fine details. Creating multiple molds from a single master and rotating between them extends effective service life by allowing each mold rest periods between uses.

What safety equipment is absolutely necessary for making soft plastic lures?

Four items rank as non-negotiable safety equipment: an approved respirator with organic vapor cartridges to protect against plastisol fumes, safety goggles to prevent hot material splashes from reaching eyes, heat-resistant leather gloves to avoid severe burns from 350°F+ plastisol, and long sleeves with long pants as additional barriers against accidental contact. Simple dust masks and cloth gloves provide inadequate protection—invest in proper safety gear before starting any lure-making project.

How much does it cost to start making your own soft plastic lure molds?

Complete startup costs range from $155-$285, including plastisol ($35-$60), silicone rubber for molds ($40-$80), pigments ($15-$25), safety equipment ($30-$50), heating equipment like a used microwave ($15-$40), and miscellaneous supplies ($20-$30). This initial investment produces 200+ custom lures at approximately $0.50-$1.00 per lure, compared to $0.15-$0.30 for commercial soft plastics. The cost premium provides customization capability and pattern preservation that justify the investment for dedicated anglers.

Why do some anglers prefer aluminum molds over silicone for soft plastics?

Aluminum molds deliver three primary advantages: exceptional durability producing 1,000+ lures versus silicone’s 25-100 capacity, sharper edge definition that eliminates flash and creates cleaner finished lures, and superior heat retention enabling advanced techniques like capsule pouring where color layers meld seamlessly. The heated aluminum surface also improves open-pour layer bonding and overall surface finish quality. However, aluminum requires CNC machining equipment or $80-$300+ purchase cost, making it more suitable for established lure makers rather than beginners.