To be honest, everything I enjoy about building pedals would vanish if I tried to make it a cost effective living. Shame really.
Essentially to make money out of it you need to take a popular circuit, say a Klone and modify it ever so slightly so you're not treading on copyright. Then get the boards made by the Chinese, your boxes screen printed somewhere and assemble big batches of the buggers here (assembled by hand in England...). Then you can slap your own bootweak name of choice on the front, wrap it in flowery BS regarding all the R&D you've done to come up with this new revolutionary stomp that'll make people jizz their pants when they hear it, slap a huge price tag on it and away you go. It would mean ignoring all your morals, but there are plenty of examples of this going on right now.
Likewise doing anything related to motorsport. Even if you own and run a top finishing team, you ain't going to make much out of it. Even then, you'll probably ruin it for yourself also.
The sad reality is that I can make a lot more money sat on my arse wasting my life away in front of a VDU. It could be much worse I suppose. But when I've eaten through a reasonable amount of my savings, I suspect that's the conclusion I'll inevitably come to.
Still, ain't going to let that spoil my time off.