Part of my to-do list this year was a custom cutting board that would fit over Becca's beloved farmhouse sink. We chose walnut to match the kitchen island, and purchased the material at Schutte lumber, which is probably one of the coolest stores for hardwood enthusiasts. Results below.
I carved out some notches with the table saw to get the perfect fit. The board ended up being 1.5" thick to strike level with the countertop.
To keep the board from moving around too much, I also added a few rubber grippers on the bottom of the board. A basic 3/4" drill made the cavity for a secure fit.
My buddy Orion and I have made several boards in the past year. There are easy ways, and hard ways, to make a cutting board. This version is an example of the easy way. One wood source, one round of gluing, and side grain (vs. end grain up). It all depends on the look you want and how much work you want to put into the project. For more cutting board ideas, you should check out his work.