I have learnt a lot about FDM by printing with and tuning my own 3D printer (a Creality Ender 3), for which I use Ultimaker Cura to generate gcode from STL files. I also have experience using Formlabs Form 2 SLA printers, an Objet polyjet printer and Lotus laser cutters.
Sometimes, nothing beats getting hands-on with making things! Having spent as much time as I could in the D&T workshops at school, and continued using manual tools both at university and at home, I know my way around most common workshop hand tools and power tools, and have used them to make all kinds of wooden, metal and plastic parts - here are just a few examples.
Some of my more recent projects have incorporated significant amounts of electronics, which has allowed me to design and prototype circuits, particularly with the Arduino and Raspberry Pi platforms. Although my degree is based on mechanical engineering, I also took the opportunity to study optional modules in electronics to broaden my knowledge.