Fully printable 608 roll bearing v2

**Improvements:**

- The axial forces are supported by the rollers in place of the housing.
- Stronger housing (1.5 instead of 1 mm and inner facets).
- Another 4 mm wheels.

**TODO:**

- The rolls have 2x0.1 mm axial play, maybe 2x0.05 would be better.
- There are also less clearance between the outer and the inner race than the rollers have in radial direction...)