Tea Light to 3/8th inch dowel rod adapter ver2

thingiverse

This is an update to my first pass at this project. I successfully matched the bottom piece's size to the dowel rod's dimensions, but now it's a bit too big. I increased the height of the top cup to fit a standard LED tea candle, still, it's slightly oversized. I'm puzzled about what's going wrong. My measurements are precise in millimeters and export as an STL that appears massive in my printing program. Normally, I scale down objects by 50% or even to 49% to achieve the desired result. This might seem trivial, but I'm using a straightforward design for a learning exercise, assuming less complexity means fewer potential issues. Am I doing something wrong?