|I found these, the bottom is solid so I just trim the ends to give the trucks room to move, drill 2 holes and holes in the plate with a tempered bit, secure with flat bolts, then its set.
I like the idea using UHMW plastic, I'm not sure yet on the heaviness of it. My idea changed to this image, So I hollowed it all out:
Pretty much Gambins idea! But I thought I would make a 2 inch long notch, 1/4 inch or so deep to clasp on. Then the outside edges I could knock off with a 45 degrees slant to ease getting on/off. Was thinking now just triangular shaped notch. But I'm not sure of freight costs for it and I must watch my money now.