I posted this earlier on comp.robotics.misc, but thought I might get more insight here. Sorry if you read both groups...
I'm looking to build something for myself and would like some input. I want a device I can hook up to my household plumbing to allow me to control temperature and pressure of my shower instead of just Hot and Cold. Ideally it would have temperature sensors and motor-controlled valves. The temperatures sensors would try to hold temperature somewhat constant. Of course a few safetys would be needed as well, ie if the device fails it should not allow water to pass etc.
Any suggestions or pointers for the mechanical part of this design?