Drilled them myself, lots of cutting oil on a mid size pedestal drill press, used 4 sizes for the 1/2" holes, started small, 3/16", 3/8", 7/16" and finished with the 1/2" holes.
I modified it by making main tube strictly a support member. I moved the bow riser support rods to a twin tube assembly using a 1 3/4" tube welded to another 1 1/2 tube that can be moved to precisely position the riser support rods for any particular bow design. One end of the 1 1/2" tube was drilled and cut open for the pivoting arm the same as the original plans called for in the horizontal tube. I ended up having to drill one more hole closer to the pivot point in each arm due to raising the arm pivit an additional 1 1/2".
I modified it by making main tube strictly a support member. I moved the bow riser support rods to a twin tube assembly using a 1 3/4" tube welded to another 1 1/2 tube that can be moved to precisely position the riser support rods for any particular bow design. One end of the 1 1/2" tube was drilled and cut open for the pivoting arm the same as the original plans called for in the horizontal tube. I ended up having to drill one more hole closer to the pivot point in each arm due to raising the arm pivit an additional 1 1/2".