Hmmm, I've been thinking about something similar, more manual, but less complicated:
It's not exactly
one button, but two buttons in one housing, a mom-off-mom rocker switch.
You can probably get one in an automotive store as a replacement for a power window switch. I'm thinking of using it as an engine on/off switch: hook it up to relays, rock forward - engine on, rock back - engine off.
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e·co·mod·ding: the art of turning vehicles into what they should be
What matters is
where you're going, not
how fast.
"... we humans tend to screw up everything that's good enough as it is...or everything that we're attracted to, we love to go and defile it." - Chris Cornell
[Old] Piwoslaw's Peugeot 307sw modding thread