history of the workmate here if you are curious.
The Black & Decker Workmate is a portable workbench/vice that has been sold in the millions around the world. If you are interested in these and do a bit of research, you find out the early ones are considered by many to be the best, as they have a pair of cast aluminum H frames that could be folded under the top to allow the workmate to be stored flat. Later models went to steel parts that were somewhat less sturdy, and certainly less cosmetically appealing.
In the USA, one of the more desirable models is the "79-001 Type 2". This model seems to be nearly the same as the WM625 version sold in the UK. (I've been told that the UK WM625 had an additional hole in each top jaw piece and that some of them lacked the "batten" on the bottom of each jaw that doubled the depth of the clamping surfaces.)
The "Bay Area Galoots" have done a type study of the various versions available in the USA.
And here is an early review from Popular Mechanics (Aug 1975):
A common thing is to make a plywood top with a 2x4 screwed to the bottom. The 2x4 can be clamped in the Workmate jaws to be particularly sturdy.
The top isn't in horrible condition for being 40 years old, but I'm considering making a new one.
So I took some time and sketched out the dimensions of the top. I thought these might save others some time, so here they are. Both halves of the top are the same.
Dimensions of the top and hole placements: