This is a slider for sled chairs and stools that use 3/8" diameter round rod for their feet. It holds the felt size that is standard for the OEM glides used on this size, such as are found here:
https://chaircaps.com/products/sfwd38-superfelt-sled-base-replacement-felt.html
The wider triangular profile of these caps acts as an outrigger, keeping them from rolling over, and thus radically prolonging the life of the felt, which usually is peeled off from the side when the cap rolls.
I printed these in PLA, four sets of four, several years ago, and have only had one failure. Note that the felt is held in with adhesive, so a material like nylon may not hold.
stool_foot.STL | 20.0KB |