How to Make Plastic Bait Molds: A Complete DIY Guide

Creating your own plastic bait molds transforms ordinary fishing trips into showcases of personalized craftsmanship.

Whether replicating discontinued favorites or designing entirely new patterns, mastering mold-making gives anglers complete control over lure color, size, and action.

Understanding Plastic Bait Mold Fundamentals

Plastic bait molds serve as the foundation for producing soft plastic fishing lures like worms, crawfish, swimbaits, and creature baits.

These molds capture every detail, from subtle ridges to lifelike appendages, ensuring each cast produces consistent results.

Types of Mold Materials

The material choice dramatically impacts durability, detail quality, and production volume.

Here is the updated content with the requested term added naturally.

Silicone rubber remains the gold standard for DIY enthusiasts, offering flexibility that makes demolding effortless while capturing intricate textures.

Aluminum molds deliver glossy finishes and sharper edges, eliminating the flat appearance common with rubber alternatives.

For general info, both options have distinct strengths: choose silicone for complex shapes and easy release, and aluminum for durability and superior surface finish.

Open Pour vs. Injection Molds

Open pour molds allow gravity-fed pouring, perfect for single-color baits or simple layered designs. Injection molds require specialized injectors but enable multi-cavity production and complex color patterns with cleaner seams.

Essential Materials and Equipment

Gathering the right supplies prevents frustrating setbacks mid-project.

Core Mold-Making Materials

• RTV silicone rubber: Platinum-cure formulas last longer with minimal shrinkage. Costs typically range from ₹849-₹1,299 per kg in India
• Master bait model: Either an existing lure or hand-carved prototype from wood
• Mold box or frame: Foam board, wood, or purchased containers create boundaries for liquid silicone
• Petroleum jelly: Acts as release agent preventing silicone from bonding to the frame
• Mixing cups and stir sticks: Silicone requires precise catalyst ratios (typically 10:1)

Plastic Pouring Supplies

• Plastisol: Liquid plastic compound that cures when heated to 320-350°F
• Heat source: Microwave, electric griddle, or metal pouring pot
• Pyrex or borosilicate glass cups: Withstand high temperatures without cracking
• Infrared thermometer: Ensures precise temperature control
• Colorants and flake: Liquid pigments, powder pigments, and glitter create custom patterns
• Injector (for injection molds): Specialized tools like N2 Series injectors push plastisol into closed molds

Safety Equipment (Non-Negotiable)

• Approved respirator mask: Heated plastisol releases fumes requiring proper ventilation
• Safety goggles: Protects against 325°F plastisol splashes that cause severe burns
• Heat-resistant gloves: Prevents contact burns
• Long sleeves and closed-toe shoes: Adds critical protection layer

Step-by-Step: Creating Silicone Rubber Molds

Patience during mold construction pays dividends through hundreds of perfect pours.

Step 1: Prepare Your Master Model

Clean the master bait thoroughly, removing dirt or oils that compromise detail transfer. Add custom features like 3D eyes or fins using modeling clay, ensuring firm attachment.

Step 2: Build the Mold Frame

Construct a box slightly larger than your master model using foam board sealed with hot glue or wooden sides. Line the interior with aluminum foil for easier silicone removal. Position the frame at a 5-10 degree angle by placing foam underneath one end—this allows air bubbles to float away from the master during pouring.

Step 3: Apply Release Agent

Coat the frame’s interior with a thin petroleum jelly layer, avoiding the outer edges. This waxy barrier prevents cured silicone from permanently bonding to surfaces.

Step 4: Mix and Pour Silicone

Measure RTV silicone and catalyst according to package instructions (commonly 10:1 ratio). Mix slowly to minimize air incorporation. Pour steadily over the master model until covered by ½ inch of silicone. Tap the frame gently to dislodge trapped bubbles.

Step 5: Cure and Release

Allow 24-48 hours for complete curing, though times vary by product. Peel away excess silicone from the frame edges. Carefully work the mold free using a hobby knife if needed, then extract the master model. The cavity left behind becomes your production mold.

Adding Registration Points

Press small beads or marbles halfway into the first mold half before pouring the second layer. These create alignment pins ensuring perfect closure during production.

Pouring Soft Plastic Baits

Transforming liquid plastisol into fish-catching lures requires attention to temperature and timing.

Heating Plastisol Properly

Cut pre-colored soft plastic worms into 1-inch chunks if recycling old baits. Place plastisol in heat-safe containers and apply medium heat, stirring with popsicle sticks until liquefied. Target 320-350°F for optimal flow and curing. Colors lighten slightly when melted, so test batches first.

Open Pour Technique

Preheat aluminum molds on a griddle to improve color bonding in laminated designs. Pour slowly into cavities to prevent air pockets, slightly overfilling to compensate for shrinkage. Allow 10-15 minutes cooling before demolding. For dual-color baits, pour the belly color first, let it partially set, then add the back color while the griddle remains on to fuse the layers.

Injection Molding Method

Secure mold halves with bar clamps ensuring tight alignment. Heat plastisol to 325°F for injection work—slightly cooler than open pour. Load the injector and push plastisol through the sprue hole. “Top off” the sprue as plastisol draws down into cavities, preventing voids. Wait until completely cool before opening clamps and demolding.

Color Mixing Secrets

Temperature matching proves critical when shooting multi-colored baits. Both colors must reach similar viscosity or they won’t blend cleanly at the seam. Use a vacuum chamber to remove foam and edge bubbles before pouring, creating crystal-clear finishes. Add flake after heating to preserve sparkle intensity.

Advanced Techniques for Professional Results

Elevating baits from functional to phenomenal requires mastering nuanced methods.

Capsule Pouring

This technique creates baits with internal color chambers. Aluminum molds produce cleaner capsule edges than silicone due to sharper cavity walls. Pour the outer color first, rotate the mold to coat the cavity walls, then inject the core color.

Scent Integration

Mix worm oil scents directly into heated plastisol before pouring. Some makers apply scent to cured baits and place them in sealed bags for 24 hours, allowing absorption.

Salt Loading

Roll cured baits in salt immediately after demolding to create a textured surface that disperses scent and adds weight. Salt-infused baits sink faster, appealing to bottom-feeding species.

Laminate Security

Proper lamination prevents colors from separating during use. Keep molds heated during multi-layer pours so each addition fuses chemically with the previous layer rather than just sticking mechanically.

Benefits of Making Your Own Molds

The advantages extend far beyond cost savings.

• Design freedom: Recreate discontinued classics or invent entirely new patterns impossible to purchase
• Color customization: Match regional forage or water clarity with unlimited color combinations
• Cost efficiency: Bulk plastisol costs pennies per bait compared to retail prices
• Sustainability: Remelt torn or damaged baits indefinitely, eliminating waste
• Competitive edge: Fish patterns nobody else possesses, especially in pressured waters

Common Risks and Solutions

Awareness prevents expensive mistakes and potential injuries.

Safety Hazards

Hot plastisol burns rank as the primary danger. At 325°F, spilled plastisol causes severe skin damage instantly. Always work in well-ventilated areas as heated plastisol off-gasses potentially harmful fumes. Never allow water or other liquids near hot plastisol—violent reactions occur.

Quality Issues

Storage Concerns

Cured baits exposed to direct sunlight or trapped in hot compartments deteriorate rapidly. Store finished lures in laminated worm bags in cool, dry locations. Separate colors prevent dye migration between baits.

Choosing Between DIY and Commercial Molds

Budget and production goals determine the wisest path.

Silicone DIY molds excel for anglers perfecting designs through iteration. The low material cost (₹849-₹1,299 per kg of RTV silicone) allows unlimited experimentation. Once a design proves effective, upgrading to CNC aluminum molds makes sense for serious production.

Commercial aluminum molds range from simple single-cavity designs to complex multi-cavity injection systems. They eliminate the learning curve of mold-making while providing professional results immediately. However, customization remains limited to available designs.

Key Takeaways

• RTV silicone rubber offers beginners the best balance of detail capture, flexibility, and reusability for creating custom molds
• Plastisol temperature control between 320-350°F ensures proper flow and curing without degradation
• Safety equipment—respirator, goggles, gloves—prevents serious burns and inhalation injuries when working with 325°F plastisol
• Aluminum molds produce superior glossy finishes and withstand higher production volumes compared to silicone alternatives
• Temperature matching between colors creates seamless lamination in multi-colored injection baits

Frequently Asked Questions (FAQ)

How long do silicone rubber molds last before needing replacement?

Quality RTV silicone molds withstand hundreds of pours when properly maintained. Platinum-cure silicone outlasts tin-cure formulas due to superior heat resistance and minimal shrinkage over time. Avoid using sharp tools during demolding and clean molds with mild soap between uses to maximize lifespan.

Can I use a regular kitchen microwave to heat plastisol for bait making?

Yes, microwaves work effectively for small batches using borosilicate glass (Pyrex) measuring cups. Wattage variations mean heating times differ—monitor temperature with an infrared thermometer rather than following strict time guidelines. Dedicate the microwave exclusively to bait making as plastisol residue is difficult to remove completely.

What’s the safest way to dispose of excess or burned plastisol?

Allow plastisol to cool completely until solid, then dispose of it as regular trash. Never pour liquid plastisol down drains as it solidifies in pipes. If plastisol accidentally burns and produces heavy smoke, evacuate the area immediately until fumes dissipate completely.

How do aluminum injection molds differ from open pour molds in terms of results?

Injection molds create baits with cleaner seam lines and allow multi-cavity production for faster output. They require specialized injectors and clamps but produce store-quality finishes. Open pour molds suit simpler designs and single-color baits, offering easier operation for beginners at lower equipment costs.

Why do my two-color baits separate after a few casts?

Poor lamination typically results from temperature mismatches between colors. Both plastisol batches must reach similar viscosity—if one is significantly hotter or cooler, they won’t chemically bond. Preheating aluminum molds on a griddle also improves color fusion by preventing rapid cooling at the interface.

What temperature range works best for different plastisol brands?

Most bait-making plastisols perform optimally between 320-350°F, but specific formulas vary. Always follow manufacturer instructions printed on packaging. Use an infrared thermometer for accuracy since visual assessment proves unreliable. Overheating above 350°F causes discoloration and degraded physical properties.

How can I prevent air bubbles from ruining my finished baits?

A vacuum chamber removes trapped air before pouring, yielding crystal-clear baits. Without vacuum equipment, pour plastisol slowly into mold cavities and tap molds gently to coax bubbles to the surface. Maintaining proper 320-350°F temperature prevents excessive foaming during heating.