The minimum size for all BaseParts is being lowered from (0.05, 0.05, 0.05) to (0.001, 0.001, 0.001). Look at these tiny little parts.
0.05 thickness on the left, 0.001 thickness on the right
The only catch is that while a part can be smaller visually, the physical collision geometry of the Part will still not go below the existing limit of 0.05. So part collisions, touch events, raycasts, etc. will still see the part as if it’s minimum dimensions are 0.05.
We expect that this is fine for most cases, as parts this small either don’t need collisions at all, or the difference in having a larger collision geometry is negligible. Regardless, we plan for this discrepancy to be “temporary” (a lot of work needs to be done first) and one day precise collision geometry will be possible at this itty bitty size.