Befaco Knurlies are M3 screws specially designed for Modular Synthesizers. The special thing about them is that they can be screwed by hand, Phillips, lotted and hexagon socket wrench. In addition, each screw has its own washer to prevent scratches on the modules. The Knurlies come in a pack of 100.
If you tinker a lot with your module layout, or even if you just add or replace occasionally, these are so much easier then screws it's surprising anyone still bothers with the latter. Excellent.
If you didn't already know, Knurlies are finger tightened bolts meaning you don't need to run around looking for a screwdriver every time you want to move modules around. They're very comfortable and I'm already thinking about getting some more so that I never run out!