I use a dog kennel with 2x4 openings in the wire and an attached roof. The bottom 3 ft are also covered in hardware cloth. I use combination tumbler locks in everything. Surrounding the whole set up and a 500 sq ft chicken yard/duck pool is electrified poultry netting. The yard us also covered in heavy duty bird netting. I have a LOT of predators here, though. Like a lot.
With raccoons, as others have said: hardware cloth, some sort of roof, latches/locks.
Electricity works wonders, and is pretty cheap. An energizer, some fence wire, some insulators, and a battery, solar, or plug-in energy source, and you're good. One hotwire at the bottom of the fence, one a few feet up, and one at the top.
I really thought it would be difficult to set up the electric, but it wasn't at all. And the energizer was the most expensive bit at around $100. But it's been going strong for years now on a rechargeable battery.