Designed housing assembly to accept 8mm OD silicone tubing and printed both components of the pinch-valve. Installed everything on a small servo. The clearances on the interlocking divots are too conservative; more engagement is needed. If the silicone elasticity/friction is not enough to lock the servo in the closed position, these divots will be required, but for now, the lack of engagement is OK. Ordered the softest silicone tubing I could find for a preliminary test.