SpudFiles

Nah I don't have any machining stuff here, not even a lathe. Or a drill press for that matter
I could try PVC as a start to see how it performs then maybe make a metal one.

I can't believe I missed this. it even mentions my use of unbalanced 3ways,
so the first design is more complicated and uses more seal than necessary and doesn't work, so here's a rule of thumb for designing a 3way 2 position valve that uses o-ring seal or any sliding seal design

If you are building a 3way 2position valve with an unpressurized or un-balanced vent:
you only need 1 sliding seal to create an unbalanced valve,

you only need 2 sliding seals to create a balanced valve

since the seal is sliding over a gap when switching positions you might encounter a brief intermediate position were the input is still leaking in while the valve is trying to exhaust, this gets worse with a larger gap so unless you can some how widen the seal the only way to get rid of it is by adding one additional sliding seal

so I would advise that you keep an eye out for anything with a sliding seal then attach ports on it to create an unbalanced 3way

The o-rings in my original post were on the wooden dowel.

You designs are very interesting... seem pretty easy to make...

So to make it ballanced you added the other sliding seal on the right to balance the pressure?