Jake - you're right on. That's what I did, and despite my amatureish woodworking skills, I had a sizeable, lightweight, box I could stand on that held up very well for two seasons. Cost was under $100

1"x1" frame covered in doorskin (1/8"?). I rounded the edges with a router, laid up a bit of glass on the edges, and coated the whole thing with polyester.

The only spots that got ugly were the drop doors on the ends because I didn't glass them right.