It’s expandable to any size simply by making it taller. You can make it as large as you want by eliminating the base and attaching it to a wall.
Glue the bottom holder rib ¾” from the bottom of the back piece and clamp until dry.
Place a CD jewel case against the first rib and add two business cards to the top. Glue and clamp the next rib in place. The business cards will ensure there is enough space to easily insert and remove the CD jewel cases.
Continue this process, being careful not to shift the previous rib.
Allow the complete assembly to dry and trim the top with a handsaw to match the last rib.
To attach the base, drill two countersunk pilot holes into the base ⅜” from the back edge and 1″ from the sides, then screw it to the back. If necessary, drill pilot holes into the back through the pilot holes in the base before screwing the pieces together.
For added strength, drill countersunk pilot holes at each rib (Fig. 2) and screw the back and rib pieces together.
OPTION: Make this holder any height you want.
TIP: Since the ribs will eventually be screwed on for strength, apply the glue sparingly and allow it to tack-up slightly before putting the rib in place. This will reduce the clamping requirements.