Printer : Print Rite DIY
Rafts : No
Supports : Yes
Resolution : 0.2
Infill : 20 %
Notes : Printed in PLA.
I recommend 3 or 4 perimeters for strength and 3 or 4 top/bottom solid layers.
I printed from the side because I think is the best way for making holes for axle holders fit properly. I prepared files also for being printed regularly. If you print the roller from the side you will need to attach LEGO knobs after, because knobs can't be printed sideways.
For axles, I first intended to use M3 bolts but then I found 3,5x30 mm wood screws which work even better (both can be used). For the central part, I used M3 bolt with proper nut and secured it with super glue.
I just spray painted the roller because I didn't have any yellow filament at the time when I print it.