Remixed these bicycle grips to make guitar stand end caps. Original design by Povhill. My guitar stand is the "Fender Universal A-Frame Guitar Stand for Electric and Bass Guitars". I made the inside diameter 1 - 3/16 inches and included scaling info for these common sizes:

1" - 84%
1 3/16" - 100%
1 1/4" - 105%
1 3/8" - 116%
1 1/2" - 126%