In general, and discounting actual mechanical problems like drive belts, electronic device failures are usually:
- Knackered batteries
- Dry capacitors
- Bad connections
- Software problems
Most of these are eminently fixable if you know what you're doing, but in order to diagnose and repair them you have to get past the plastic tabs and/or glue that modern devices are inevitably held together with, which is often destructive. Which means that 90% of consumer electronics problems come down to whether you're able to repair or replace:
- Snappy plastic parts
Which is where the 3D printing comes in.
I've lost count of the times I've fought my way inside some failed device, diagnosed the failure with little more than a Mk 1 eyeball, and promptly given up because I've destroyed the case to get to it, so now the buttons won't work or it isn't waterproof any more or whatever. The world would be a better place (at least in WEEE terms) if people just used fucking screws.