Is it possible to use a piece of 1 x 1 square tube stock instead of the 1/2" piece of plate steel in the jig?
Everbilt 1 in. x 72 in. x 0.0625 in. Square Tube 801127 - The Home Depot
A square shaped hollow rod, a square tube is the alternative to the round tube. Square tubes are typically used for framework, gym equipment and awnings. Available in various sizes and materials. Square