Truly Mad Plastics sells a kit for white edible markers that you fill with americolor food gel. I have it and it is great! http://www.trulymadplastics.com/store/#!/Chalkboard-Paint-Pen-Kit-02-Extra-FINE-Tip-0-7mm/p/49838301/category=12825209
Jennifer, https://www.facebook.com/PrimaCakesandCookies