To bend all four sides of a metal box I made a tool for the metal "brake" (i.e. bender ) (figure 1)
The "fingers" of the brake interfered with the final bending of the box (fig 2,3)
I solved the problem with a (hot rolled) steel angle bar cut and notched fig (4,5)
The bar replaces the fingers of the brake, entering from the box end instead of the side.
The bar was cut and shaped with an abrasive chop saw (figures 6 & 7)