Wilton products are all kosher but unfortunately, they have heaps of preservatives in them. I use them heaps, but when I was failsafe, I generally did a mix of either chocolate frosting or white.... sometimes I would mix in beetroot puree for a bright pink colour. You could mix in a bit of sweet potato puree for orange as its a sweet flavour, but it would only be a light orange/mustard yellow because you don't want to put too much in. If you are worried about effecting the flavour, add some vanilla bean paste to it. That makes it all yummy and you could use nuttelex for an easier consistency.

oh! I forgot about those, you could get the melts from Wilton and melt them into moulds and put them on as well, and they are kosher.