This is a small solid cube with a spherical void inside it. This is useful to find good settings to obtain a truly transparent print on FDM printers before trying something larger and more advanced like cymon's skull dice.

I also provide a model with small drain holes if you want to print this on an SLA/DLP printer (where obtaining true transparency should be quite a bit easier than on an FDM printer).

The print shown is transparent ABS, but any transparent filament should work if you do the following things:

• 100% infill, obviously
• Print with a bit of over-extrusion (not too much, just enough to ensure air bubbles are pushed away from between the layers)
• Print slowly
• Print hot, with just enough cooling to keep the print from turning into one messy blob.
• Printing in thin layers may help as well.

Natural PLA should also work to a certain degree, although its transparency is limited and will look milky for thicker objects. Polycarbonate, PETG, and Colorfabb HT are probably the best choices for a truly transparent print, although pretty good results can also be obtained with transparent ABS.

Printing on a glass bed will allow you to quickly see whether the print looks decent, because the bottom surface will be very smooth. If you can see the sphere through it, chances are that it will look good after polishing. If it looks milky or you can see air bubbles with a magnifying glass, there is no point in polishing it, you'll have to try again with different settings.