I built this general purpose bench for in the parking area of the garage. As you can see it works well to collect junk. Anyway, it has a plastic laminate office cube table surface as a benchtop, which has a +1" this fiberboard substrate. Flat and easy to keep clean. I use 90 degree, 8-9" long right angle "stair tread" brackets from the home center. They are thick, strong steel, between 1/16-1/8" thick, secured to frame and top with 1/4" lag screws in pre-driled holes.
The frame uses Douglas fir 4x4 at the corners, accepting snug fit 2x4 in lap joints, secured with carriage bolts. The handles on the right legs are half lapped pieces of 2x4, cutting the height of the 2x4 down at the grabbing portion is optional. But that half lap distributes the handle lift load off the wood screws some and onto the lap joint.
The magic is at the non-swiveling casters, installed of the posts opposite the handles. I think they are 3" diameter, beefy ones. I secured the casters to pre-drilled holes to accept at least a 2.5" lag screw. The space between the 6:00 position of the wheel and the ground is finger thick, as low as possible but leaving enough meat in the 4x4 for the bottom lag screws.
See it, see it...? This little bench moves just like a wheelbarrow. Lift the handles to get the wheels on the ground, and drive it wherever you'd like. No movement of the bench when stationary due to casters always on the ground. And if you have a machine bolted to the top, with the bulk of the weight located at the wheel end, you'll be able to move it around just like you would a loaded wheelbarrow. Making it longer increases your mechanical leverage advantage moving it around.
Building diagonal braces into the frame, or installing a skin of plywood, would create a nice, rigid framework to mount a lathe or other power tool.
