German designer and architect Felix Grauer crafted this handmade key hanger and organizer from his bin of standard LEGO bricks. Though he doesn't provide a how-to specifically, the photo details the specifics:
- One 8x16 flat plate in gray
- Several 1x1 and 1x2 in black for "KEYS" (or whatever you'd like to spell)
- 3-5 1x4 Ø4,9 (Technics) for the key chains
- 3-5 key rings
To attach it to the wall, I'd recommend a basic 3M Command Strip.