Hi fraser, also another problem area where pieces are not meeting up cleanly is in this spot:





So there are 3 areas (2 along the sides, I posted a screenshot of 1 side earlier) where there were some kind of little gaps or misalignment between pieces which has resulted in some little slivery surfaces.

I've nearly got a solution for you (which will include some small slivery surfaces in those areas though), one trick I used was to temporarily scale your sink down by 1/10 in size which also shrinks the gaps between edges to put them within join tolerance. Also I drew a circle that was just barely larger than your bottom hole and trimmed the basin surfaces to it to give them a good juncture.

- Michael