How to make a Flat 90 degree bend in Electrical Trunking, nearly cutting thumb off in the process... This step by step guide to follow or not in the case of my thumb. This is made to measure. This method uses an angle grinder although an hacksaw would be also as good (the method I normally use to demonstrate to students in a class safer). Looks as good or better than a bought one. Lid not shown but would be the same method as the trunking. Simples.