Guitar slides in S, L, M and XL sizes that are more or less what you would encounter in a music store.

Inner diameters and lengths:

Size S - 17mm inner diameter, 55mm long

Size L - 19mm diameter, 59mm long

Size M - 21mm diameter, 64mm long

Size XL - 23mm diameter, 72mm long

All sizes are 1.5mm thick, which should make them rigid enough to sound good.

Print vertically. I'd suggest using a brim for stability, but removing it may be annoying. YMMV.