Three attachments change what an injector can do: a C-block mixes two colors into one mold for camo and marble patterns, a dual injector keeps two colors separate in one mold for true laminates, and a manifold splits one color into two to four molds on a single shot. Master the basics first, then add the one that matches the bait you want to make.
Start with the shot itself
Every trick below rides on one thing: getting hot plastic into every cavity before it starts to set. If your single-color pours are coming out short, bubbly, or seamy, no attachment is going to fix that. It will just give you variations of the same problem.
Four fundamentals, in order of how much they matter:
1. Temperature. Plastisol converts from liquid to usable plastic at just over 350°F. Once it is converted, inject in the 300°F to 350°F range. Inject too cool, and it sets in the mold before it fills the entire cavity. Too hot, and you scorch the plastic and get yellowing, or dents can develop in your bait.
2. Pre-warm the injector if needed. A cold aluminum tube pulls 20 or 30 degrees out of your plastic instantly, which is why so many people's first pour of the night is the toughest one.
3. One smooth stroke. Push steady and firm, not in stages. Stopping mid-shot can leave a visible seam where the first stage of plastic started to skin over before the second flow caught up.
4. Hold pressure for a beat. Keep your hand on the injector knob for two or three seconds or longer after the mold is full. Different cavity styles may determine how much pressure and time is needed. Plastisol shrinks as it cools, and that extra pressure is what keeps the plastic flowing. Finding the right amount of pressure is key; too much pressure may cause the mold to flash.
The PTFE lining on the A.i. Premium Single Injector exists for one fundamental reason. It insulates the tube and nozzle so the plastic holds temperature longer, which is the difference between injecting 1-2 molds per fill and injecting 3 to 5. The 6 oz injector runs $174 and fits any two-piece mold with standard 5/8" ports.
If injecting itself is new to you, start with How to Make Soft Plastic Baits at Home and What Is Plastisol, then come back here.
The three attachments at a glance
| Attachment | Colors | Molds per shot | What you get | Price |
|---|---|---|---|---|
| C-block | 2 | 1 | Camo, marble, and swirl patterns | $89 |
| Dual injector | 2 | 1 | Clean top and bottom laminates | $459 complete, $174 conversion |
| Manifold | 1 | 2-4 | Increases the amount of baits per shot | $69-$89 |
Read that middle column carefully, because it is the whole story. Two of these tools give you more color in one bait. The third gives you more baits in the same amount of time.
C-blocks: two colors, one mold, one pattern
A C-block sits between your two injector nozzles and the mold, and it lets the two streams tumble together on the way in. You are not trying for a clean line here. You are trying for the mottled, camo, sporadic look that a green pumpkin over black or a watermelon over red gives you, where no two baits come out identical.
That last part is the appeal. Store bought baits are uniform by design. A C-block batch is uniform in feel and different in every single bait, and people notice.
Sizing is the only thing you have to get right. C-blocks are matched to the distance between your dual injector's nozzles, measured center to center:
- C-Block 2.25" fits Do-It Molds dual injectors with nozzles 2.25" apart. $89.
- C-Block 3.50" fits Angling Ai Premium Dual, BassTackle and N2 injectors, and any dual injector with nozzles 3.5" apart. $89.
Measure yours before you order. Nozzle center to center, not the outside width of the bracket.
Pro tips for C-block pours:
- Pair one opaque and one translucent color. Two opaques fight each other and read as mud. An opaque base with a translucent partner gives you depth in the pattern.
- Vary your push speed on purpose. A fast, even push gives you a tighter, more blended pattern. A slower push with a slight hesitation gives you longer streaks. Once you notice this, you can steer the look.
- Do not overthink the ratio. Both injectors will not empty evenly, and that is fine. Uneven is what makes it look natural.
- Run the darker color in whichever injector you fill last, so it goes in slightly hotter and streaks more readily.
Dual injectors: two colors, one mold, a clean line
A dual injector does the opposite of a C-block. Instead of mixing the streams, it delivers them side by side so they stay separate in the cavity. That is how you get a dark back over a pearl belly, which is the single most convincing thing you can do to a soft plastic baitfish.
The Angling A.i. Premium Dual Injector is the complete system at $459: two 6 oz PTFE lined injectors (12 oz total), the PTFE lined blending block, the bracket with locking pin, the ergonomic injection bar, a hex tool, and four replacement O-rings. Assembly runs about 10 to 15 minutes.
If you already own A.i. Premium Single Injectors, the Dual Injection Conversion Kit gets you there for $174. It includes the blending block, bracket with locking pin, injection bar, and hex tool. It only fits Angling A.i. Premium Injectors, so check what you have before ordering.
Pro tips for laminate pours:
- Contrast is everything. Light over dark or dark over light. Two colors of similar value produce a bait that just looks slightly off instead of looking like a shad.
- Both injectors need to be at the same temperature. If one sat longer than the other, the cooler color will lag behind and your seam line will wander. Pre-warm both. Viscosity will also play a factor. Some colors may be thicker than others, Make sure that both colors are about the same consistency.
- Put the color you want to see on the injector that feeds the visible side. Which side that is depends on the mold. Shoot one test bait before committing eight ounces of plastic.
- Molds built for it work better. Anything described as dual injection ready or laminate capable has the runner geometry to keep the streams separated. The RipRap, Hammer, Pin Point, Phantom X, and the 3" and 3.5" Tracer Shad all fall in that group.
For the deeper version of this technique, including running a third color through the middle of the bait, read What Is Core Shot and How Do You Pour It.
Manifolds: one color, two to four molds, one shot
This is the new one, and it solves a different problem entirely.
Everything above is about making a prettier bait. A manifold is about making more of them. It splits the output of a single injector across two to four molds so both fill on the same stroke. One color, a number of molds, one shot.
Why that matters more than it sounds like it does. The bottleneck in a pour session is almost never your hands. It is the cooling curve. You have a window from the moment the plastic leaves the pot to the moment it is too cool to fill cleanly, and everything you do inside that window is productive while everything after it is reheating. A manifold does not make you faster. It makes each shot count double, which effectively widens that window.
When a manifold is the right upgrade:
- You pour the same color in volume, like a pearl or a green pumpkin you burn through all season.
- You run two to four of the same mold designs.
- You are filling orders, stocking a club, or getting ready for a tournament season and quantity is the point.
- You have already got your single color technique dialed in, and reheating is your main frustration.
When it is not:
- You mostly pour laminates or camo. The manifold is a single color tool. A dual injector or a C-block is your upgrade.
- You pour small test batches in a lot of different colors. You will spend more time cleaning than you save.
- Your molds have larger cavity volumes than your injector can inject.
Pro tips for manifold pours:
- Match the molds by total cavity volume to your injector.
- Clamp both molds before you start. Using the bolts and nuts from Angling A.i. is ideal.
- Size up your fill. Two molds means roughly double the plastic per shot. Plan your pot volume accordingly and do not try to stretch a single 6 oz fill across a pair of large molds.
Quick troubleshooting
| Problem | Most likely cause | Fix |
|---|---|---|
| Short shots, unfilled tails | Plastic too cool, or pressure released too early | Inject at a higher temperature, hold pressure longer |
| Visible seam across the bait | Stopped and restarted mid-shot | One smooth continuous stroke |
| Air bubbles in the bait | Air pulled in while filling the injector | Purge the injector and fill slowly |
| Laminate line wanders | Two injectors at different temperatures | Fill both injectors after checking viscosity |
| C-block pattern too muddy | Two opaque colors, or push too slow | Pair opaque with translucent, push faster |
There is a longer version of this in Why Are My Soft Plastic Baits Bubbling or Tearing.
Which upgrade should you buy first?
If you own one injector and want better looking baits: the Dual Injection Conversion Kit at $174. Cheapest path to laminates if you already have A.i. Premium Injectors, and laminates are the upgrade people notice first.
If you are starting from nothing: the A.i. Premium Injection Bait Making Starter Kit at $379 gets you injecting, then add from there.
If you already run a dual injector and want more looks: a C-block at $89. It is the least expensive way to add a whole new category of bait to what you can produce.
If you already have the looks you want and need volume: the manifold, when it lands.
FAQ
What is a C-block used for in soft plastic injection?
A C-block sits between a dual injector's two nozzles and the mold, letting two colors of plastisol mix on the way in. It produces camo, marble, and swirl patterns where no two baits come out identical. C-blocks are sized to the distance between your injector nozzles, measured center to center, commonly 2.25" or 3.50".
What is the difference between a C-block and a dual injector?
Both use two colors in one mold, but they do opposite things with them. A C-block mixes the two streams together for a mottled camo pattern. A dual injector keeps the streams separate so you get a clean laminate, like a dark back over a pearl belly.
What does an injector manifold do?
A manifold splits the output of a single injector across two to four molds, so both fill on the same shot with the same color. It does not change how a bait looks. It increases how many baits you get per injection, which matters most when you are pouring one color in volume.
What temperature should plastisol be when you inject it?
Heat plastisol to just over 350 degrees Fahrenheit to fully convert it, then inject in the 300 to 350 degree Fahrenheit range. Below that it starts setting in the runner before the cavity fills, which is the most common cause of short shots and unfilled tails.
Why do my injected baits have a seam across them?
A seam almost always means the injection stroke stopped and restarted. The first slug of plastic begins to skin over before the second catches up, leaving a line. Use one smooth, continuous push and hold pressure for two to three seconds after the mold fills.
Pick the attachment that matches what you want to make
The honest summary: a C-block makes patterns, a dual injector makes laminates, and a manifold makes volume. None of them replaces good temperature control and a smooth stroke, and all three get dramatically better once you have those.
Have a look at the injectors and attachments page, and keep an eye out for the manifold.
Make Your Baits, Your Way.
By the Angling A.i. team · Updated September 2026