/diy/ - Do It Yourself

Thread almost dead, but I'll try anyways.
How feasible is it to make your own liquid dispension system consisting of a cylindrical flat system with multiple in/outputs which is rotary encoded. Pic to explain: I thought about taking plexiglass or some shit and cutting a circle in it, then drilling channels at a 90 degree angle. If you now turn the inner circle you can "choose" the output. The problem is I want no leaks and to be so tight that the air pressure in the connected pipes still is contained (we're talking low pressure) pic for reference.
Are there things like that that cost little or will I have to build it myself? Is it doable? Ideas?

I need a way to distribute liquid. Essentially I want to run multiple liquids with one pump. Is there a (cheap) way to do that?

Pic is what I thought about . Multiple tubes for the liquid, one stepper motor inside to choose the tube you want. Problem is: I don't want to /can't prime the pump, everytime, so is it possible to get something like this where the pressure in the tubes isn't lost? (In my pic I tought about rotation of a disk to choose the tube.