Hey Caspar,
this machine blows my mind and gives me shivers, when Otto is using it. Really tricky how you assembled the controls and not even mentioning the effects it is capable of.
I just bought an PS-3 and want to modify it kind of like you did, not that I have your skills or much practise..
My goal is pretty accomplished if I sort out the in's/ out's/ power supply and my most favorite part, the JOYSTICK (not self-centereing ones are hard to get here..) to control both pitches. Anything beyond that is even more awesome, but I'd be happy with these "basic modifications"
I will use every advice you shared on this page/ your website about it, but if  you got a spare one about this especially, I would be more than pleased. Thanks for the inspiration.
Feel free to hit my email anytime.
Cheers Paul