This portable clamp-on bench is remarkable. Chris Schwarz wrote an excellent article on making a great reproduction of it in the June 2013 edition of Popular Woodworking Magazine.
Mine is not an exact copy. The original used wood screws, mine uses steel. All the wood in mine is 2 by 4, or 2 by 6 hem from the local home store. Round dog holes contain stubby dogs cut from dowel and pushed into close fitting 3/4" holes. The clamping method to attach the bench to a table or workbench is amazingly simple, but very strong.
I've also worked out and built a sturdy knock-down, portable base for it.
More to follow, but as I'm writing this on an iPad, and haven't figured out how to put pictures in a blog this way, you'll all have to wait.