I have one of those big plastic cutting boards. It is a pain to wash, rinse and store this sized cutting board. I wanted something smaller for a quick onion or pepper chop so I decided to make one.
This is made from Maple scraps I had laying in the shop. I used yellow glue. (I highly recommend using a waterproof or outdoor type glue) and finished with a food safe wood finish.
Step 1: Cut and mill your lumber
I cut 6 pieces about 1.25" wide 1" thick and about 10" long. My table saw is square enough and my blade was sharp enough to get these square, the first time around :)
All of these dimensions are based solely on what I had in the scrap pile and the size I had in mind, so go crazy if you want . Most all regular cutting boards are made in the same fashion.