This app is awesome (so much better than manually doing it in Blender), especially the ability to easily make blanks and export with fin supports but if you're still updating stuff there's a few things it'd be cool to see:
1. OTF support - a lot of free fonts come in OTF format and the app currently isn't compatible. Additionally some TTF fonts cause the app to absolutely freak out for no apparent reason and a vertically-scrolling error log appears, although the information often doesn't explain what the problem is in simple terms.
2. Numbers centered to each face - currently a lot of the numbers wind up very offset and need to be individually tweaked which can get pretty tedious when you have to do it for every face of every die.
3. Alternate D4 "teardrop" shape - Twisting the small un-numbered faces 45° with respect to the numbered faces looks really cool (see attached image)
Additionally, some of the dice are exported from the app with broken geometry and require fixing in Netfabb before they'll adequately print. The D8 winds up missing an entire chunk of its mesh if sliced before fixing.
