This is a 3D printable adapter for the Elecom Huge that lets you replace the static bearings with roller bearings.
This model is not perfect and improvements can be brought to it, that's why I've provided the .step file as well. So anybody could modify and bring additions to it. You will need to source your own MR63-6x2.5mm bearings for this adapter, 4 to be exact. Ideally a trackball should only require three bearings positioned equally around the ball cup. Unfortunately, due to the limited space inside the Elecom Huge, a perfect placement of three bearings is impossible, that's why I've added a fourth one to support the ball. Printing should be done with supports. I find it best if the print is placed upright. Be careful when removing the supports, especially the ones around the screw holes at the bottom of the ball cup. If there's some material left over from the supports, the ball cup might not sit flush to the bottom of the case and the ball will end up snagging on the top of the case.
You can also find the files on MakerWorld