I have a dish drying rack that had a bamboo knife block for safely holding knives as they dried. Moisture eventually caused the block to split, so I modeled it using TinkerCad and printed in my P1S.

I added a stop on the bottom to prevent it from sliding into the rest of the utensils area of the rack. If I were to change anything, I'd probably design it thicker to make it more stable as you are inserting and removing knives.