A pretty easy workbench made out of some 2x6's, a piece of 3/4" plywood, and a piece of 3/8" particle board. It's something that my Dad designed that we put together.
Step 1: Parts
As for the size of the workbench, the table top dimensions and table height is completely arbitrary. It can be pretty much any size you want (I'd guess that the table top should be no bigger than a 4X8 sheet of plywood). The table top size for this Instructable will be 6.5 ft X 2.5 ft. For that, here's what I needed:
2X6 Wood Boards: 6' cross beams x2
2' leg braces (dog eared) x6
30" legs x6
39 Feet total
3/4" Plywood: 6.5' X 2.5' tabletop bottom
3/8" Particle Board: 6.5' X 2.5' tabletop top
*note: The table top dimensions are a half foot longer than the cross beams and leg braces. I picked these dimensions because I wanted to have about 3 inches of overhang so that I could have a place for C-Clamps, etc.
2.5" deck screws (or something close that length than has a flat head): x33
4.5" bolts: I think i used a 3/8" diameter bolt with nuts and washers x24
Step 2: Assemble Legs
Align a leg with a leg brace. The top of the leg should be flush with the top of the leg brace. The leg brace should extend 2 inches past leg. Drill 2 pilot holes and secure with 2 bolts. Repeat at the bottom of the leg. Secure another leg at the other end of the 2 leg braces. Complete this leg assembly 3 times.
Step 3: Attach Cross Beams
Using the deck screws, I attached 2 cross beams to each leg assembly. The cross beams are 6 feet long so this defines how far the outer legs are spaced. The middle leg can go anywhere in between. For mine, I placed the middle leg about 20 inches from the right leg so that I could have some leg room. I also attached the front beam on the inside of the front leg assemblies, again for leg room. I don't think it matters that much structurally. With the beams resting on the tops of the leg braces, I put 3 screws in each leg. I attached the back cross beam to the outside of the back leg assemblies.
*note: As seen in the picture, I faced the left and right leg assemblies inward so that the leg braces wouldn't interfere my 3 inch tabletop overhang. It also provides more support for the tabletop.
Step 4: The Table Top
Secure the table top to the leg assemblies with deck screws. The table top is aligned so that there are 3 inches overhang on all four sides.
To attach, I put 3 screws through the plywood tabletop into each leg brace. 9 screws total.
Next, I glued the particle board tabletop to the plywood tabletop with wood glue. I made sure there was enough glue near the edges. I clamped the two pieces together and used some weights on top to dry.
Finally, I put two more screws through the entire tabletop into each leg brace. 6 screws total.
Then I put a "Done" stamp on it.