How to Build a Garage Work Bench (with Pictures) - wikiHow Build a Sturdy Floating Shelf to Use as a Workbench. to Build a Garage Work Bench. 1. Attach a long 2x4 (38×89 mm) horizontally to the wall studs. (If your wall is solid brick, stone, etc., this method will not help you). The length of the 2x4..