I've seen blacksmiths make forge stock stands using a trick: the stand's
vertical member is a tube (e.g. 1/2" pipe) and the vertically adjusting member
is a rod (e.g. 1/2" round bar) which slides in the pipe. The top of the pipe is
cut at an angle and there is a washer slipped over the pipe. As you lift the
pipe, the washer rattles down, but when you let go of the pipe the washer is
forced to an angle and binds on the pipe. When you get it where you want it,
then (and only then) does the user tighten the threaded T-handle clamp on the side.

My question is, does anyone know how to design this angled washer setup? How
angled should it be? How much bigger than the vertical rod should the hole in
the washer be?

Grant Erwin -- trying to not reinvent the wheel