A while back, I bought a folding chair from the thrift store; I think it cost $2. The only thing it lacked were the rubber tips for the feet. After rummaging through our doodads and scraps, I came up with a solution which used:
a piece of pipe that would slip over the ends of the chair legs
washers that would fit inside the pipe but not the chair legs
a stick (probably maple) from my husband's stash
Pieces of the stick became the new chair feet, which I slid into sleeves cut from the pipe. The washers keep the inner ends of the sticks out of the chair legs. The double-sided tape went around the chair legs to help the upper ends of the sleeves stay on.
So the actual handwork was only sawing and filing and a little whittling. I used a hacksaw to cut the pipe, and rounded and smoothed the cut edges with a file (a metalworker's file; almost exactly the same technique as filing your nails). I sawed the stick with a regular saw, whittled it down to the right diameter, and rounded the edges at the end with the file as well. Then I put it all together, and the new chair feet are working well.