I've done almost everything bad under the sun.
- added a second pickup with improper tools
- diy defretting
- diy fretting
- diy shielding
- nut adjustments
- routing an output jack to the lower side of a bass
- sanding down a bass body (only to find out I didn't like how it looked)
- ripped out a 4 string bass bridge to try to fit a 5 string bridge
- ripped out the electronics of a bass to put it onto another and burned many pots and wires in the process
- unstrung the ends of strings to use on a short scale bass
- drilled holes into pick guards to fit more "stuff"
- making a bridge string-hole bigger so that a low F# string can fit
- .. the list goes on
Reflecting on it though, I learned a lot, but a lot of time and money was wasted. I'm going to have to agree with this quote:
After years of modding and thousands of dollars lost my main regret is all of them. If you don’t like the way your bass sounds find something else that fits the bill. Basically everything you could want is currently available.
A. Never mod a bass if you can't bring it back to it's original form (for resale purposes)
B. Save and get what you actually want instead of buying something cheap with the intent of "upgrading it"