The original model by Will is a neat design and I wanted to make it for some beginning sewing students. However, the “spool ends” (the top and bottom of the container) are slightly different thicknesses (2mm and 2.2mm). Because both parts are in one file, it's not possible to print it as-is and do a nice clean color change. Also (possibly related), one of the parts isn't quite flat on the print bed in the file.

I used 3D Builder to “fix” and split the model so both parts are flat on the print bed. I then cut .2mm off the bottom of the part with the taller base so that the bases are the same thickness. That way when you print you can print both parts together with a single filament change.