Step 2: Cut the pieces
Like I wrote in the last step, these pieces were cut with a laser cutter so it was quick and precise. Just use the attached files and you're good to go.
If you don't have a laser cutter, which you probably don't, you can use one at a local TechShop, or get them cut at Ponoko.
Barring that, you can always do it by hand as well. Yes, it will take a lot longer, but it's an option.