I've seeing strange results in the export to STL preview, not sure if it's a real problem for just a break up in graphics, using OSX beta.
Notice the 3 leaves on the left are not showing triangles? , the left side was made by mirroring the right side. I delete the whole left side, re-mirrored it same results.
Hi steve, there is something wrong with those ones - if you zoom in really close to their tip you can see that it's kind of messy there:
That thing that looks like a tiny squished flat edge actually appears to be a slivery thin tiny additional surface, and a degenerate face like that will interfere with calculation of the outward facing surface normals. So probably that little tiny face will need to be removed and the points of the large one squished down to a single point to make that into a proper solid without any degenerate things in it.
I think the revolve and flow, would be an easier method, I think I used sweep with 2 rails and had a few problems ;) ( when I get a chance I'll pull up the old files and have a look at what method I used :) )