10 Cent Piston Pump

The 10 Cent Piston Pump is a compact 3D-printed syringe powered pump block that uses two nickels as simple, effective check valves.

This design turns a syringe into a directional piston pump, with fluid moving cleanly in one direction thanks to gravity- and pressure-actuated coin valves. It features three standard 1/8" aquarium tube ports (inflow, outflow, and syringe).

ℹ Printing instructions:

Print at 100% infill to ensure watertight channels and strong walls.

There are two stages where you’ll insert nickels mid-print ("fast-finger" or pause). The correct moments should be clear from the print progress and model geometry.

Once printed, the coins are sealed permanently inside, creating a no-maintenance, one-piece fluid block. Just connect tubing and a syringe to start pumping!

🪄 Tips for improved performance

Coat the valve contact side of the nickels with a thin layer of Plasti Dip, RTV silicone, or liquid electrical tape, and allow it to fully cure before inserting into the print. A “rubberized” metal surface on PLA will dramatically improve the seal and reduce leaks — especially if you can achieve a smooth, even finish.

Choose smooth filament. Different filaments have different surface textures. Filaments with a rough surface (e.g., fibers, matte blends) will increase internal flow resistance. For best results, use glossy or smooth-finish filaments and avoid any that contain fibers or fillers.

Maximize printer accuracy. The better the dimensional accuracy and consistency of your printer, the more reliable the valve seats and channels will be. Carefully tuned extrusion, bed leveling, and Z-offset all help.

Experiment with syringe volume. The syringe you choose will affect the flow profile and overall performance. Smaller syringes provide quick, pulsed bursts; larger syringes create smoother, slower "breathing-like" flows. Try different sizes to match your needs.

Double up for smoother flow. You can print two pumps and operate them on opposite phases (one drawing in while the other pushes out) to achieve a more continuous and steady flow profile.

💬 Tubing & flow optimization crash course

When setting up your pump, the type and layout of tubing can dramatically affect performance:

Rigid vs. flexible tubing:

• Rigid tubing (like PTFE or stiff PVC) holds its shape under pressure, preventing "ballooning" and keeping your flow sharp and responsive — great when you want precise control.
• Flexible tubing (like silicone) is easier to route and less prone to cracking, but it can expand slightly under pressure, which softens or dampens the pump pulses.

Adding a pressure bladder (pulse dampener):

You can add a small flexible "bladder" or expansion bulb just after the pump outlet. This acts like a capacitor in an AC-DC rectifier circuit, smoothing out pulsations and creating a steadier, more continuous flow.

Minimize connectors:

Every connector, elbow, or Y-split adds flow resistance and potential leak points. Fewer connectors = smoother flow and less maintenance.

Choosing wisely:

• Pick rigid tubing for short, straight runs where precise pulses matter most.
• Use flexible tubing if you need to make gentle curves or avoid vibration-induced cracks.
• Combine them if needed: rigid right after the pump, flexible near bends or end connections.

⚠ Notice:  The ACTUAL cost is more than 10 cents.  The name is derived from the use of 2 nickles.  The cost of materials will vary depending on what you use.  At 100% infill, it uses just under 35 grams of filament.  If your filament is $15/kg, this uses about 50 cents worth of plastic.  You will also need tubing and a syringe.

🎨 Aesthetic Tips:

Use a spare syringe with a fine blunt tip, load it with paint in a contrasting color, and fill in the debossed text on the top, making it easier to see and read.

📝 Designer’s Notes

This project is meant as a fun, functional experiment and educational tool rather than a drop-in replacement for commercial pumps or valves. It truly workss (even in early tests with bare nickels!), but it’s important to understand where it shines and where it falls short.

🌟 Where it excels

Educational demonstrations: Shows check valve logic, gravity-assisted sealing, and piston pump principles in a tangible, hands-on way.

Small fluid experiments: Perfect for hobby setups like small aquaponics, DIY dosing systems, or moving small amounts of liquid between containers.

Maker and tinkerer projects: Great for people who love hacking, prototyping, or learning about fluid dynamics without spending a lot.

⚡ Where it might fail

High-pressure or high-volume systems: This design isn't meant for continuous heavy-duty use, pressurized closed loops, or industrial flow rates. If you're thinking aquarium main circulation pump or lab-grade fluid delivery — look elsewhere!

Zero-leak or medical-grade reliability: Even with coated nickels, the seal is not as perfect as silicone or precision-engineered valves, and small weeps may occur over time.

High-precision dosing or metering: While it can move repeatable volumes, it isn’t designed for ultra-fine measurement accuracy.

✅ Practical performance factors

Results depend heavily on your printer’s accuracy, filament choice, tubing layout, and how you actuate the syringe.

Expect to experiment a bit — that’s part of the fun and learning!

💬 Final thoughts

This is a low-cost, approachable way to explore fluid control using mostly 3D-printed parts and a couple of nickels. It’s not trying to compete with professional lab gear — it’s about empowering makers to understand and play with fluid logic in a tangible way.

If you go in with the mindset of "I want to learn, experiment, and have fun," you’ll have a great time. If you need flawless continuous flow at 3 bar of pressure... you'll probably end up with a wet workbench. 😄

💬 Development Log & Results So Far

1. Alpha model — First prototype; poor fittings prevented reliable operation.
2. Beta model — First iteration (Published) — Used bare polished nickels. It works, but with noticeable backflow; more fluid moves forward than backward, proving the concept but far from ideal.
3. Beta model — Second iteration — Currently in progress; working on improved coin surface coatings for better sealing.

Coin coating attempts so far:

1. Bare + Liquid Electrical Tape: Poor adhesion, peels easily.
2. Bare + Scuffed + Liquid Electrical Tape: Still poor adhesion.
3. Bare + Scuffed + Superglue sub-layer + Liquid Electrical Tape: CA glue holds, LET does not.
4. Bare + Scuffed + Superglue+TPU Disk: Pending.

⚡ Community call!
If you experiment with different coatings or treatment sequences on the coins (e.g., alternative rubbers, dip coatings, different primers), please share your results in the comments!
I’ll gladly add any successful (or even partially successful) methods to a shared list here, with full attribution — whether under your real name, pseudonym, or anonymously. You’re also welcome to include one link (e.g., project page, social profile) if you'd like.

Coin Coating Methods & Outcomes