Some of my most-go websites

Sonic Bloom
No. 1 blog on Ableton Live, Push & Max for Live with tons of tutorials and freebies run by former Ableton tech support Madeleine Bloom. She provides in-depth video courses, Live and Max for Live Packs as well as services like one-to-one lessons via Skype, mixing and mastering.

Jez Filey French's contact microphones
Making your own contact microphone is easy, making great ones like those is another story. I am impressed by the quality of those microphones and for that price they are far the best I could find.

Keith McMillen
I am a fan of their controllers, I use the SoftStep, QuNEXUS and QuNEO

Teensy
My favorite Arduino IDE compatible microcontroller

Adafruit
I like their products and particularly the way they are documented. When I am looking for some electronics, I often start there

Stepper motors
Those are cheap, good quality, arrive well packed, quickly and have a nice data sheet for each motor.