Step 1

Drill the Screws Into the Blocks
Glue a 7"x2"x1" block of wood to the top of a 7"x 4"x1" block. Don't center the top block: glue it to one side. Drill the dry-wall screws through the blocks to hold them in place.
Step 2
Drill a Row of Holes
Use the various bits to drill their own holes. Drill a row of holes into the top block, then a row of holes into the bottom block.
Step 3

Write the Bit Size
Use a pencil or thin marker to write the bit size over its hole.