Programmable Knex Piano-Playing Robot

Step 2: Build Right and Left Base Modules

Build two of these, a right one and a left one. They're exactly the same except for the two yellow rods on the right side of the left module. See the picture for more details.

NOTE: I didn't have enough yellow rods, so I used the gray rods that are the same length as the yellow ones. I needed to make several substitutions, so the colors may vary.