Sometimes makers come across products that they’d love to buy, but which are too expensive to justify. When that happens, the natural inclination of the maker is to build a DIY version. Such projects often end up costing way more — in both time and literal currency — than the product would have. But when we get lucky, we can save some money. That’s the case with this spiral clock built by Kelton.

Kelton based this design on the Aspiral Clock. That product was quite expensive at $542 and the company that made it seems to be defunct now anyway. Kelton’s version looks similar and works in the same way, but only requires about $60 in materials.

This clock is a giant spiral and indicates the time with a ball that rolls along the spiral. The entire spiral rotates at a constant speed, causing the ball to move towards the center. Numbers marked along the path show the time. When the ball reaches the center, it drops through a chute that puts it back at the beginning of the spiral. That repeats endlessly in 12-hour cycles.

The electronics are very simple: an Arduino Nano ESP32 board tells a stepper motor to spin at the exact rate that Kelton calculated. That stepper motor turns the spiral, keeping the ball in motion. Because this development board has an ESP32, it would have been possible to connect it to a WiFi network to find the time and keep everything in sync. But Kelton didn’t think that was necessary, so the spiral just rotates at a constant rate.

The real trick with this clock was the woodworking. All of the parts are laser-cut plywood and Kelton made heavy use of kerf cuts. Those break up a length of wood into many segments, so the wood can easily bend. That technique was perfect for creating the smooth spiral path and the result looks fantastic.