For glasses that have a consistent angle they are actually a truncated cone and there are equations to figure out the surface shape. Attached is a spreadsheet I use to get the measurements of a template. I then divide the template into 4 sections and try to keep the design within one section. When you look at a glass, you are really only seeing about a 1/4 of it,maybe a 1/3 so if your design is bigger than that you have to rotate the glass to be able to see the entire image and can start to look unprofessional.   There are also some web pages out there that will create the template for you, you just plug in the info. I never had much luck with them, and prefer doing my own templates anyway.   Once you get the curve you then distort your image along the curve. I use Inkscape so I don't know how to do that in Flexi but someone should be able to chime in. *note, simply putting the text on the curve will not give you a true image reproduction, but will look pretty good in most cases and will at least make the text look straight. Inverted Truncated Cone.zip