Lots of cardboard
Box cutter/Hobby knife
Step 1: Cut out the pieces
This step takes a long time. I did it over the course of a week because I went through several blades and it tires out your shoulder. The cardboard gets bent and damaged sometimes but that is not a big deal.
When spray painting mine, I put a primer down first to help stiffen the cardboard up a bit. I then used indoor chrome spray paint because it sticks best.