The Apple touchpad is a wonderful device. But if either of the little 'feet' at the corners come off, it becomes unusable because the feet are actually the buttons that let you click. I lost a foot, figured the above out, and printed a replacement. It's an exact replacement, and not only pops right into place, but stays in place without any adhesive. Cool!

This thing was made with Tinkercad. Edit it online https://tinkercad.com/things/dQz11iel5oX

Print (100% fill - it's so tiny there's no point in trying to make it hollow).

Put it into the hole where you're missing a foot on an Apple trackpad.

Hold it in place, flip the trackpad over and use it. You can click!