L-shaped shelf bracket, 150 mm reach
A simple right-angle bracket for a light shelf up to about 150 mm deep, holding books, small speakers or plants in a hallway. Good geometry uses a 6 mm thick vertical leg of 150 mm, a 140 mm horizontal leg, a 45-degree gusset connecting both and three 5 mm holes per leg. Print it on its side so layers run along the legs, and give the inside corner a generous 8 mm fillet where load concentrates.
Store-bought brackets come in a handful of sizes; a generated one matches the exact shelf depth and screw spacing of your wall. Describe reach, thickness and hole layout, look at the preview, then ask for a stronger gusset or shorter leg in plain English. Testing the idea is free, and nothing needs installing.
Create an L-shaped shelf bracket: vertical leg 150x30x6 mm, horizontal leg 140x30x6 mm, joined at 90 degrees with a triangular gusset 60 mm along each leg. Three 5 mm through holes per leg, 8 mm inner fillet, 1 mm outer chamfers.