Shelf support brackets in 4, 6, and 8 in (100, 150, and 200 cm) sizes.

I suggest printing the brackets flat on the bed to improved strength. I printed with no supports, but supports can be added to get slightly cleaner top curves on the holes. Material choice really depends on the use, but keep in mind that PLA tends to creep under a static load. I chose ABS for my brackets.

If you don't use the supplied profile (6 walls & 25% infill), I suggest using something similar or higher for better strength.