I found a large C-clamp on special (around $4) at a recent trip to Princess Auto. My cheapskate bulb lit up quick, so here's what I ended up with.
All wood is doubled-up leftover 5/8 plywood smothered with leftover oil paint.
Closeup of vise, partially spray-painted.
In action...
Still need to carpet the edges, add a padded disk, shorten the bolt and finish painting the clamp.

All wood is doubled-up leftover 5/8 plywood smothered with leftover oil paint.

Closeup of vise, partially spray-painted.

In action...
Still need to carpet the edges, add a padded disk, shorten the bolt and finish painting the clamp.