I had to purchase a drill press vise recently to fabricate a canopy component. While looking for the vise I came across a 6" carpenters vise used for woodworking. There have been a number of occasions when such a vise would have been useful during the construction of the RV-8. Anyway, it was only $20 so I picked it up and installed it on one of my benches today.
The vise was made to mount on the lower surface of a workbench with an overhanging work surface. None of my benches overhang the required distance so I had to come up with a different way of mounting. You can see in the photo I made an upside down "U" shaped mount from wood. The mount with the vise attached is fastened securely to the workbench. Not the cleanest installation but it works.
Oh, I added a couple soft wood blocks to the clamping surfaces of the vise to protect aluminum parts. I think the extra vise in the shop will be handy.