Use M3 or M4 bolts to attach Multiboard or Honeycomb Storage Wall to your Gladiator GearWall.

Print them all on the side.

PETG recommended. PLA as a second alternative. ABS doesn't have great layer adhesion, which can cause premature splitting, especially on the M3 model. The top and bottom M3 holes are the most prone to stripping with any material, but even when they do, I've been unable to pull a screw out.