Skins: The skins look great. Nice job. HDPE is a lot more forgiving on the parts. You can press in stuff easier because it stretches. With acrylic, you might need to oversize the holes. On new pieces, I usually test fit the bearings before the final cutout pass, so I can adjust the holes as required.
T-Nuts: That is frustrating. I removed the section from the build instructions. I put the whole thing on the
frame drawing now. It also lists the full count and not just the extra nuts. I found that to be better. I recently built a frame and still forgot some nuts even though they were clearly listed. It is easy to get excited and move ahead too quickly.
Laser Interface Panel: You talk about test firing the laser, but say the interface panel does not work. Did you bypass the interface panel?
The system is fairly simple. You have a safety loop that connects the water pin on the laser power supply to ground. It loops through several switches. Opening any switch opens the loops and prevent firing the laser. Use a meter to check that ground water pin does connect to ground when all switches are in the run position. You can do that right at the laser PS terminal block. Many people wire the cover switch wrong. It wires differently than the limit switches. Measure continuity across each switch.
There is a simple circuit shown here.
http://www.buildlog.net/wiki/doku.php?i ... wer_supplyYou can use this to test the laser and slowly replace the wiring shown with the wiring in your machine. There are three basic items: Test button, water connection and pot. Replace one part at a time.