What I would like to do is build a run of plywood cabinets, just like you would use in a kitchen. I am planning to set them a few inches off the floor to make a toe-kick area. My idea is to have about five feet of 24" deep cabinets on the left and three feet of 36" deep cabinets on the right. The top will thus give me an L-shaped work surface. For a top, I had been thinking two pieces of 1" plywood one on top of the other, but some reading on the group has convinced me that a solid core door might be an easier idea.
I want to do this because it will kill several birds with one stone. I will get a decent bench out of it. I will also get lots of under-bench storage space, which is at a premium in my 12'x12' shop. I will also get practice in building plywood cabinets, which is good since items on my Real Soon Now list include a new vanity for our bathroom and a new island for our kitchen.
Okay, so the question is will this work? My gut is telling me that if I build the cabinets in a modular way, from 3/4" plywood with 16" wide modules and screw them together, loads on the top will see 1.5" of wood every 16", which is roughly the same support structure as a 2x4 wall. If I also screw them into a cleat on the wall, I think the structure won't be likely to move. My gut tells me surely this will be strong enough to use as a workbench, but every bench I see in books includes massive 4x4 posts and gigantic mortise and tenon joints.
I expect to use the bench for joint making, assembly and finishing. I expect the most rigourous things it will have to stand up to are chopping hand-cut dovetails and planing nearly-finished stock (I have a jointer and thicknesser for the rough stuff).
One final question... Assuming I do this, and use a solid core door as the top, I will also want to put a 2x4 skirt around the top so I will have a place to install a vise. Do I then need a solid wood door, so I'll have something to fix the skirt to? I think if the door is particle board or plywood on the inside, once I do my L-shaped cut out, the inside of the door won't hold screws, or glue, or anything.