This page has some pretty simple stuff, but it's still custom nonetheless.
Logic USF Reverse-Polarity Mod:
This is a mod for the Logic USF Shocker/Nerve frames. USF frames use a different magnet system for trigger return (the magnets are set to attract each other by using the pre-travel screw located in the top of the trigger). I wanted to go back to the reverse-polarity setup like the stock frames, so I modified the USF to allow this. The mod doesn't have much use, but it was fun to perform.
The first thing you need to do is drill a hole in the trigger guard to allow a longer drill bit to be drilled into the frame. Then you will need a longer drill bit (maybe) for the magnet hole in the trigger. Try to simulate the position on the stock frame, by holding the trigger up and seeing where the trigger magnet lines up.
The hole you need to drill has to be the correct diameter to then be tapped using a hand tap. The frame magnet is threaded 1/4-28, so I used a 7/32" drill bit for the hole. The hole in the trigger guard will have to be large enough for the tap to enter and pass through on its way to the frame.
To tap this hole, you will most likely need a longer tap than usual. It will have to be more than 4" in length, generally. The trigger guard on the USF frame is very wide so there's no way the default sized hand tap would fit, with a tap wrench installed.
Either way, once tapped the frame looks like this.
NDZ Set Screw Mod: (older triggers only)
One of the issues with the NDZ trigger is that the original versions (that were used for about two years) weren't really made to work with flipped switches. It's because they were made to provide the same benefit as the flipped switch by moving the firing point set screw downward. The problem is if you use the trigger with a flipped switch board, it's like using the stock trigger with a non-flipped-switch.
I should note NDZ altered their design after a while, and begun drilling two firing point screws so you could choose whicever one you wanted. Much better!
This mod is basically performing the same action. It involves drilling and tapping a new hole in the trigger (higher up than the stock firing point screw hole) so the screw will contact the trigger higher up on the microswitch lever. This is pretty easy to do, but it's also very easy to screw up. If you're not careful you won't drill the trigger straight and it'll look like crap. Measure 10 times, drill once.
You'll need a 6-32 taper tap, plug tap (recommended), and a 7/64" drill bit for it. Drill a hole all the way through the trigger slightly above the stock firing point screw. Tap the hole and you're done.
The trigger above was grinded down on the rear, so it'll look a little different than the stock [unmodified] one. This grinding was necessary to allow the trigger to fit on one of my markers, but isn't something you'll need otherwise.