Can confirm, 3mm is what it's in ( .135" will work). Mild steel works great, just paint it or have it blackened. You'll still need a dremel to polish the burrs off. I just had one cut, and the .dxf is good, but you'll probably need to break the parts down and increase the gaps, depending on the lasers tolerance. (I had it done on one with +/-.010" tolerance, the material had a +/-.008" thickness tolerance.) You'll still need a few printed parts, which Toad hasn't released, but usable options are already out there.
Despite the detractors, Toad's done a great job setting this up, and the frame comes out really nice. Thank you Toad!