Step 2: Create the unique part
Cut the sheet to 3.5" x 9.5", you can cut this with a utility knife.
Drill the holes for the create screws. The create screws make a box that is 2 and 5/8" by 8 and 5/8".
Drill the LEGO brick spaced holes. Use a 3/16" drill bit and I spaced the holes 16mm apart.
I laid out the sheet in a CAD program, printed it out full size and taped it to the sheet. Then I used this as a guide for cutting and drilling.