Without wanting to sound discouraging (and I'm someone who repairs and build amps for a "living")........
I suspect it's already a pretty crowded market.
Unless you are going to simply assemble kits (and there are plenty of people doing this) it will require some investment.
I fix plenty of boutique pedals, and my main criticism is that many of them look home-made rather than hand built, ie badly painted boxes, poor quality PCBs and wiring.
You also need to work out how you can gain access to the pedal market, ie can you make it cheaper than other builders (probably not), why is my tube screamer clone better than all the others (indeed assuming the world needs another TS-9 clone......), or can you offer something unique to the market (which will require R&D and knowledge of electronics) and then convince people that they can't live without it.
If you are going to do this seriously you will also need to know about RoHS, CE marking and WEEE.
Having said that, building anything is very rewarding, and not "working for the man" has it's benefits.