Potty Money

Potty Money

When my son was potty training, we wanted to give him a little extra incentive to use the toilet. We had some stickers featuring cars, construction vehicles, and other things he liked, and I came up with the idea of giving him his own little "bank card" where he could earn stickers and cash them in for treats.

Naturally, this meant designing and 3D printing something that could probably have been accomplished with a piece of cardboard.

And so, Potty Money was born.

The card has three circular openings sized for approximately 1-inch (25.4 mm) stickers, with a slot along one end for a removable paper insert. My son's name is Wesley, so I put a big W on the front and printed it in contrasting black and yellow.

The idea is simple: every time he earned a sticker, he could add it to his card. Once all three spots were filled, he could cash in his Potty Money for a cookie or some other small treat.

The removable paper insert makes the whole thing reusable, so we weren't printing a new card every three trips to the bathroom.

I realize this is a ridiculously specific design, but I figured I'd share it on the off chance someone else might get some use out of it. And if your child's name doesn't start with W, I've included the original FreeCAD file so you can customize it.

How It Works

1. Take a standard 3 × 5-inch index card and fold it in half lengthwise.

2. Slide the folded card into the slot at the end of the printed holder. The paper should sit behind the three circular openings.

3. When your child earns a sticker, they get to put it onto the exposed paper through one of the openings.

4. Once all three spots have stickers, they can redeem their completed card for a small reward.

5. Remove the index card, unfold or reposition it to expose a fresh section, and slide it back in.

Because the index card is folded in half, you can generally get four rounds of stickers out of a single card before replacing it.

The reward, of course, is entirely up to you. The card does not dispense cookies, despite what my son might have preferred.

Printing Instructions

The design consists of two separate pieces, a base and a cover, which are printed separately and glued together.

For the version shown in the photos, I used:

- 0.4 mm nozzle

- 3 walls/perimeters

- 3 top shell layers

- 3 bottom shell layers

- Variable layer height

- Black and yellow filament, with manual color changes

You don't need a multicolor printer. The contrasting colors are achieved by changing filament at specific points during printing.

Base: Black → Yellow

I started printing the base in black.

I paused the print and changed to yellow just before the raised letter and four corner posts began printing above the surrounding surface.

This leaves the main body black while the letter and corner posts are yellow.

Cover: Yellow → Black

For the cover, I reversed the process.

I started printing in yellow, then changed to black when the broad top surface began printing. In my print, the final three layers were black.

The design uses chamfers around the circular openings, the letter, and the outer edges. Because those chamfered surfaces expose the underlying yellow layers, the finished card has yellow outlines against the black face.

I think the effect turned out pretty cool, particularly considering this is essentially a fancy sticker holder.

Tip: Use your slicer's layer preview to determine exactly where to make the filament changes. The correct layer numbers will depend on your layer-height settings.

Assembly

After printing, align the cover and base and glue them together.

Be careful to keep the paper channel clear of adhesive so the index card can slide freely in and out. I'd recommend checking the fit of your folded index card before gluing everything permanently.

Once the glue has cured, insert your folded index card and you're ready to start earning some Potty Money!

Customizing the Design

I've included the STL files for printing, STEP files for anyone who wants to modify the geometry in another CAD program, and the original FreeCAD project file.

If you use FreeCAD, changing the initial should be relatively straightforward.

1. Open the included FreeCAD file.

2. Find the ShapeString object named "Edit Me for Letter" in the model tree.

3. Change its String property from W to whichever letter you want.

4. Recompute the model.

One important caveat: Changing the letter will probably break the chamfer feature around the letter on the cover. You'll likely need to remove the broken chamfer feature and manually create a new one using the edges of your replacement letter.

The chamfer isn't strictly necessary, but it's responsible for the contrasting outline around the letter, which is one of my favorite parts of the design.

Depending on your FreeCAD installation, you may also need to update the ShapeString's font-file reference.

And, of course, you're welcome to modify anything else in the design. If you want different-sized sticker openings, a different shape, or some other variation, that's why I've included the editable files.

Final Thoughts

This was one of those little parenting projects that probably involved considerably more effort than the problem justified, but my son enjoyed having his own special card, and it made the reward system a little more fun.

If someone else finds it useful, or adapts it into something entirely different, I'd love to see what you come up with.

Happy printing, and good luck with potty training! 

Updates

2026-10-23

I've added a few other letters.  I'm going to add a simple star as a generic option as well.  If you'd like to see a particular letter added, drop me a message and I'll get it added as soon as I'm able.