This is brilliant!
PVC is great: cheap, common, easy to work, and easy to join temporarily or permanently. Only problem is, it’s kinda ugly, much of which owes to the fact that it only comes in white, gray, sometimes black, and (if you’re willing to pay through the nose) clear. Sure, you can paint it, but PVC doesn’t take paint all that well, and the paint is prone to flake and screws up the dimensional tolerances. With stain, you get color that doesn’t flake or add thickness, so you can stain pipe and fittings different colors before assembly and still expect them to fit.