We have used it extensively for scopes up through 12", indeed, on a 16" and 20", most successfully. PVC is heavy in the larger sizes: you have been warned! In the smaller sizes (which we obtain free from the local PVC manufacturer from the discard pile after multitudinous offers of looks through the scopes) the tubes are held round by the mirror cell, and an upper ring if necessary. The PVC is sanded to a high gloss and painted if desired, and auto detailing added. Looks great!
Mel