Drill 2 holes in the cups and use zip ties through the peg board to keep them in place.

for the school room closet. Ballpark plastic cups become a wall of pen and marker storage. Two holes are punched into the back of the cups, then secured with zip ties through the cup and the pegboard. ¤♡¤ I would make use shorter cups

So making these for the kids room

Primary Schoolhouse Utility Decor - One is dry erase, one is a chalkboard, one is corkboard.