So far, I'm preparing the interlocks for the k40.

So far, I’m preparing the interlocks for the k40.
What should be the best wire to cut? PSU 24V, L, IN,
Relay AC? (only could be done if already got USB input)

You want to use the P+ and G as these arm the laser. It’s easy to add additional interlocks using these pins.

+Andy Shilling: Between P+ and G? Thanks!

Yes if you are not sure where they are just follow the two wires from your laser switch. Use some sort of microswitch on the cabinet door and wire it in series with the laser switch, that way you have to arm the laser and shut the cabinet before the laser will fire.

Look up the interlock chapter it explains it far better than I can.

I did, just overlook the p+ in the pic (so small) Thanks again ;D