Step 1: Materials
About spools: I was told that usually a construction company will pay a deposit of $50 USD or more per spool to the cable manufacturer, then return the spool when empty. We were lucky because in our case the manufacturer didn't want their spools back, so they became a nuisance and the foreman put them up on Craigslist for free. But when you see empty ones, never assume they're free and just swipe them, that's weaselly. In many cases you'll find that they are for sale at a reasonable price or for free, but you've got to play nice and ask. Electric companies, phones companies and cable TV providers are all possible sources for spools.
-spool: the one I used was four feet in diameter, and 32 inches tall. The inner "barrel" was two feet across.
-misc. wood: sourced from free palettes, acquired (by asking nicely) from lumber yards and furniture stores.
-galvanized drywall screws
-"door" hardware: hinges, handle, latch.
-hole saw drill bit (two sizes)
-screwdriver (or chisel, if you're one of those "right-tool-for-the-job" snobs)