NikolaToy is selling a very cool
self-balancing "Lelo" triangle. As a cost saving measure, they made the frame out of the circuit boards. This works great, except the edges of the board don't provide enough grip for the triangle to push itself upright. Instead, it slips back and forth without ever coming to balance on one of the triangle points.
Here are some "boots" you can put on your Lelo triangle. Printed in TPU (Thermoplastic Polyurethane) they're flexible enough to snugly fit on the edges of the circuit board, and provide enough grip that the triangle can easily right itself and start balancing.
These fit snugly on the Lelo triangle PCBs. Remember to order two of them.