Yes , that is a Harbor Freight flanger I used. The flange step should be the same thickness as the panel being flanged.
If the patch panel being flanged is thicker, then the flange step will be thicker than the surrounding metal.
Always dress the edges of both panels being put together. Use a file or some kind of sander to remove any distortion and burrs.
This is the first time using SPI's Epoxy, I can say it much better than Kirker Epoxy I've used and about the same as that name brand DP 90.
Hope this helps, Ed.