I use 2" and 2 1/2" pipe mainly because one slides nicely inside the other but you can go larger or smaller depending on the application. Construction is all welded. As with most weld assemblies it is important for a good look to make sure all angles are set up right before tacking things down.
Dies and tools for my sheet metal former are all conveniently stored in a scrap aluminum container on the stand.
Wing nut on the vise stands locks a sliding fit to adjust the height of the vise.
The 3 legged stance is stable in any location and can be bolted down, were anchors are provided, for extra heavy work.
I am sure I will be making more of these as the need arises.