Follow this tutorial for the how-to!
Step 1: Measuring and Cutting
The best tool for doing about 40 of these rectangle blocks is probably a chop saw. As you can tell from the pictures, I started off using a band saw, but it was taking way too long, and the cuts, obviously, weren't wonderfully straight. Chop saw all the way.
I cut about 40 of these bad boys, then sanded them to a smooth finish.