I would think the following:
- Some sort of microphone
- Some sort of test tone
- LCR multimeter
- Pen
- Paper
- Patience
You could short cut some of the initial testing with the
woofer tester from PartsExpress.
I'm about to embark on my first passive crossover soon, and think I've got all the tools needed. Hopefully, if I came up short, someone will chime in.
JCD