These are designed to level whatever is laying on them for doing things like pouring epoxy resin. Uses 1 each of 1/4" x 1.5" bolt, 1/4" nut and 1/4" washer. Set the bolt into the knob, place a washer on top and fit it through the middle piece. Use superglue to attach the middle to the bottom. You may need to do a little fitting with a file for the two pieces to fit cleanly. Fit the nut into the bottom of the top piece and thread it onto the screw.

The peg can be glued to the bottom if you use this with a clamping table with 3/4" holes. I attached a piece of no-slip foam to the top.