I recently added a large wooden bench to my shop and thought it would be a nice place to keep my "surface plate", a free granite countertop sink cutout I have had for a couple of years now. A height gauge would be nice to have too so I finally got round to making one. The base is from a dead gauge I bought on Ebay. Got it for a couple of bucks...just wanted it for the base. I pulled out an extra 8" digital caliper and started hacking off the unnecessary bits with my Dremel and made up a little extension out of a piece of 1/2" keystock for mounting the scriber. The scriber itself is actually one of the jaws I cut from an old dial caliper I had lying around that was well past any other useful purpose in life. I milled away a bit from the bottom for clearance and attached it with a couple 8-32 screws. It is pretty darn accurate as shown by one of my better 1-2-3 blocks:

A better view of the granite plate:

And a closeup showing the scribe:
