If you can find a Craftsman shop vac at a garage sale, you don't ned to fabricate a plywood lid. A hot knife & a couple screws & wing nuts, Good to go!
Jsut picked one up yesterday for a whopping $2! Now just gotta get off my butt and put it together!
I put one together. The leaf blower cost me $20 last summer at a garage sale. The shop vac was free. I spent an additional $10 for parts like spray foam, etc.....jim