Adjustable pentagonal shelf support

thingiverse

When I need to add an internal shelf or a shelf in a niche, I never get to drill holes perfectly level, and even so, plain wood shelves are hardly perfectly plane. I've designed those supports so they have five different heights (in 2 mm increments) depending on how you rotate them. You normally need to print 4 units. Before you tighten the screws, put the shelf on and rotate as needed.