I found this nice vase on Thingiverse and printed it at 75% scale a couple weeks ago.

75% scale vase looks fine from this angle…

It came out pretty good except for the area near the bottom where it was overhanging.  3D printers don’t handle overhangs without support material very well.  I tried reslicing with support material added, but didn’t like the way it looked in either Cura or Slic3r so I didn’t try to print it again.

Overhang caused poor print quality for the first 6-8mm of the vase.

Then I tried printing it upside down- the overhang is much smaller.

100% scale vase printing upside down.

About 12 hours later, here’s the result:  perfect!

The two vases, bottoms up- the 100% scale vase is perfect!