I made one for FIL, 114diam chs, think it had 10mm plates top and bottom. Top plate was cut same shape as the base of the vice. Bottom about 250x250, bolted to the floor.
I've made one for my small leg vice its an 14" square 3/4" plate (I found in the middle of the road) for a base and a piece of 2.5x2.5x1/4 channel for the post with a small piece of plate for the vice bracket to mount to, its not fastened down to the floor as I wanted it fairly portable. With it being a leg vice I can bray on it no problem.
Definitely worth the effort, it means you bash thngs without everything jumping about on the table. Mine is in the right hand corner of this pic.
Made of 30mm box section, I left the ends of the horizontal bits open and they are great for bending bits of bar.
Since this was taken I have fitted a rack to hold files and various hooks for grinders, hacksaws etc.
I was gping to bolt it to the floor, but fid it more convenient to be able to move it occasionally
I've a stand, a Record TS5 RV, tripod with a cone in the bottom you clamp three legs into, there is a bolt that goes up in to the base, the Record 1 tonne vice bolts to the top.
I quite like Chunko's. It's well accessible and portable. It's not the best pic though Chunko! I'm sure I've seen one of your threads with a better pic in it somewhere...
The last shot was teken two and a half years back, just after moving in still as tidy as that just more lived in these days.
Here we have ye vice stand thingy.
Every now and again I find myself adding new bits to it, hooks for saws and grinders, holders for bolt croppers etc.
Chunko'.
This is my girlfriend's vice stand, Record No.6 on pipe and plate with a lug for an earth clamp
The top plate's well scarred which is a handy place to hang my chipping hammer. Bottom plate's 50mm which means it doesn't fall over, it's really easy to roll around the yard though
The next job is to stick a torch/electrode holder bracket on it