90mm (diameter) x 22mm (width) Mecanum wheels, as used on our robot "Tigerbot" in PiWars 2018.
PiWars has a width limit of 225mm, and the motor/encoder/gearboxes (Pololu 25mm gearmotors) used up most of it. It was impossible to find commercially available mecanum wheels narrow enough to fit on the robot (and they cost a fortune), so we ended up designing our own.
The Rollers were printed in RigidInk TPU. I printed them vertically with a brim and used the sequential printing option (i.e. finish a whole roller before starting the next) to avoid stringing between the rollers. You need to allow lots of space between them for the print head to fit between them - I got 16 at a time on my Prusa print bed.
The Frames are simple PLA. The two halves bolt together with M3 nuts/bolts. There are 3 bolt holes for mounting the wheels onto a 25mm cylindrical hub (not included in these files) which attached to the motor with a grub screw. The rollers are attached to the frames using 26mm dressmaker's pins (I found it helped to drill out the holes in the frames with a pin drill first). The pins are held in place with a dab of epoxy on the head - but check that the roller rolls freely before you do that!
For a 4 wheeled robot, you will need 2 sets of the 2 wheels in this package - a pair of clockwise wheels and a pair of anti-clockwise wheels. You mount them on the robot so that the pairs of the same wheels are on diagonally opposite sides.
3D FilaPrint FilaPrint Fluorescent Orange Premium PLA
The above settings were for the Frames.
The Rollers were printed in Rigid Ink TPU, 0.2mm, 15% infill with a 2mm brim.
I printed them vertically and used the sequential printing option (i.e. finish a whole roller before starting the next) to avoid stringing between the rollers. You need to allow lots of space between them for the print head to fit between them - I got 16 at a time on my Prusa print bed.