Here's a general list of resources & links that may be useful to you!

The most useful thing you can get from this is to get into the habit of searching stuff up! There are so many resources out there and this page can only cover so much.

Finding 3D Models & Libraries

GrabCAD — Community library with literally any 3D model you can think of
SnapEDA — Footprints & symbols for electronics components (though creating your own when possible is recommended)

Useful Software

Excalidraw — An awesome site for making really quick sketches that look good
KiCAD — Free, open source PCB design software that works on any platform
Fusion360 or Onshape — For 3D modelling

Technical Resources

Ellis' 3D Print Tuning Guide — Swaths of really useful information for dialing in your prints
Keyboard Atelier Designer Spreadsheet — Reference data for keyboard designers

Project Inspiration

Adafruit — Hundreds of insanely cool projects with full guides and tutorials

Communities

Discord servers:

KiCAD — PCB design help and discussion
QMK — Keyboard firmware
VORONDesign — 3D printing community dedicated to VORON designs

Subreddits:

r/mechanicalkeyboards — Keyboard help and showcase
r/QMK — Keyboard firmware discussion
r/3DPrinting — General 3D printing community
r/electronics — Electronics projects and help

Measurements List

These are common measurements for designing 3D printed parts:

Part	Measurement
M3 screw head diameter (socket & button head)	6mm
M3 heatset inserts	4.7mm OD, 4mm depth
M3 screw-ins for plastic	2.9mm
M2 screw-ins for plastic	1.9mm
M3 SHCS screw head depth	3.1mm
M3 BHCS screw head depth	1.8mm

Most of these were taken from the VORONDesign team's designs — they work well across other designs too.