Reuleaux Polygon Wheels & Coins - 3D Printed Toy Set

The toy they will ask about long after the party.

Product pictures are made from the 3D model, not photographed.

$9.99

Plus $7.95 flat shipping to US addresses.

Color: Gray

How many

Made to order. We print it in the USA after you buy, so print time comes before ship time.

Flat $7.95 shipping. Made in the USA. Broken or wrong? Send a photo within 30 days and we reprint it.

What it does

Build rolling non-circular wheels that actually work using geometry magic
Print replica British 20p and 50p coins with constant-width shapes
Learn why sewer covers don't fall through their holes, it's math!
Perfect educational toy for geometry enthusiasts and curious tinkerers
Includes multiple Reuleaux polygon designs ready to print and explore

Ever wonder why sewer covers are round? Turns out circles aren't the only shape that won't fall through their own hole. Meet the Reuleaux polygon, a family of constant-width curves that roll, work as coins, and make brilliant 3D printed toys for anyone curious about geometry in action.

This design file lets you print working non-circular wheels that actually roll smoothly, create your own versions of British 20 and 50 pence coins, and explore the same math used in real-world engineering. Reuleaux polygons are used in everything from currency (like the Mauritian 10 rupee and Jordanian dinars) to manhole covers that can never fall through their openings.

Perfect for makers, educators, or anyone who loves a good geometry puzzle, these pieces snap together to demonstrate constant-width curves in a hands-on way. Roll the wheels, stack the coins, and impress your friends with the smarty-pants answer to that classic engineering riddle.

1.6k downloads in the maker community. That is interest in the design on the site it came from, not our sales.

How big it is

Size: 15 × 15 × 1 mmsmaller than a coin
Made: In the USA, printed when you order

Sizes come from the real model file, not a guess.

What you get

One printed piece, in the color you pick.
Nothing else to buy. It works as it arrives.

What it is made of

PLA, printed in one solid color. Compare the materials.

Printed plastic is strong for its size, but it is not metal. We have not load tested this design, so we do not publish a weight rating. Keep it out of a hot car and away from open flame.