Here's a shot of the under side. I cut the existing frame and modified the vertical angle of the handlebar collar to be perpendicular with the ground so it wouldn't jam up when it pivoted. Geometry is critical here.I had to used plate steel and bolts to join the frame because of no welder. I reinforced the 1/2" plywood top with sections of 1/2" conduit that where flattened and bent in my bench vise. They were secured to the frame with sheet metal screws and eye bolts. I used cap nuts to finish the connections off to look right.