Foot for Grip Tools 59070 Jumbo 24" Aluminum Caliper

I picked up one of these giant calipers at Harbor Freight a few years ago. Recently I've been using it to level the gantry on a 3D printer, but the end face wasn't the flattest so it would rock a little.

This foot goes on the end of the caliper which then sits on 3 points. In the pictures version the caliper sits too close to the front. I moved the caliper slot back for better stability.

I don't see these available at Harbor Freight anymore, but they're available online for about US$1