This model is a massage roller.
There are for wheel types you can chose. In total you need to print 1 handle, 2 items of the wheel type you want and 2 pins.
The two wheel parts are assemble together with the pins to make one complete wheel. You can either assemble them superposed or shifted (see illustration).
They are assembled to the handle with a 20mm M3 screw.
Everything can be printed without support.