I made jack stand mounted to the edge of the workbench. It works great as an adjustable support for holding my rifles. I can also put a clamp on the top of the jack to help hold the rifle in place too. Made this several years ago and do not know what I would do with out it.
The link below shows all the parts involved, with measurements.
Link:
http://www.hootalrifleshop.org/jack_stand.htmHoot AL