Surely there is an engineering/tool supply shop local to you for pillow blocks & collared bearings, belts and pulleys. Any 'Steel & Tube' should sell 19 mm stainless tube (used in dairy sheds) by the meter.
Your wiper motor should have plenty of torque and negate the need for pulleys to gear down a higher RPM motor.
Farrell Bearings in Hamilton have everything you will want if that is an option. Farrell Bearings
If you don't want to make the barrel this is an easy if expensive option. Barrel Tumbler | Tumbler Barrels | Rotary Barrel
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