I am a vegan and trained as a pastry chef. If you are serious about starting a vegan cake decorating business, I strongly suggest taking a course to learn basic techniques/use of various tools of the industry, then veganizing recipes for your own use. Also, laws (aka Health Inspectors) are pretty strict in terms of what you can prepare at home, but one option would be "personal cheffing" where you cook in other people's homes for them, doing up a week's worth of food, etc. I also would recommend McCall's school of cake design in Toronto at Bloor/Kipling, which offers intense courses, many aimed more for the professional, as opposed to the home decorator. Good luck, I hope you succeed....I'd love to do something like that!