I realized the necessity of making a knockdown bench about halfway through the design process. Otherwise, I would never be able to get the bench out of the basement. For a bench to be knockdown, the goal is to turn it into 5 pieces, the top, the two side assemblies, and the two long front stretchers. Also the bench has to be just as stout as its non-collapsible counterparts. I bolted through the legs into the front stretchers, where I have a matching nut embedded in it. That was the easy part, but the problem was still how to attach the top to the base. At first I planned on making through tenons, like the traditional Roubo (see this stunning specimen), but then reality set in. So I decided to make a sort of cleat system that is bolted to the underside of the bench. I have completed this, and it works very well, I made 1" long and 2" square tenons on the top of the legs, but they were probably unnecessary.
Most of the ideas were from Christopher Schwarz's free chapter on knockdown workbenches.