If you enjoy variations in the size and shape of the knobs this is the vibrator sleeve for you. It utilizes a small mini bullet style vibrator. Small enough to fit discreetly in a purse or travel bag. Suggest printing at .2 mm layer height with supports. Due to variations in printers you may want to use some electrical tape to make sure the vibrator is snug in its hole.
50.5 mm widest diameter, 96 mm tall, vibrator hole: 18 mm diameter, 35 mm tall