Step 4: Make the Wings
So with my 1-square to 1 foot ratio, I cut the pieces with a hacksaw. Aluminum is pretty easy to cut this way. To make the hinge holes 'correctly' you want to use a drill press so everything is a perfect 90-degree angle and all the holes fit nicely.
But what I HAD was a drill. So I carefully employed the old Mark I eyeball, and did the best I could. Just mark off with a sharpie and make your holes as perfectly vertical as you can. It can be a good idea to pick up a metal file to take any sharp bits down. Nobody touched the wings, but you never know.
To prevent a lot of the trouble associated with imperfectly vertical drilling, I put a washer in between each member when I bolted them together.
(Important note: I used steel nuts and bolts. Steel and aluminum will corrode if kept in contact with each other due to their 'galvanic number'. In practice, this probably won't affect a normal hallowe'en-only usage for several years, if at all)
Once the holes were drilled, I had two 'wings' that would fold and unfold.