I am wondering if anyone has ever used melted Wilton candy melts to pipe on buttercream or fondant.

No one?? I'm thinking of giving it a try. I like how they set up and they taste good. Plus the colors are nice.

I think that's a great idea! Don't see why it wouldnt work! I want to try it now too! Good luck!

I have used it a lot--I do the chocolate instead of the frozen buttercream transfer...same way, just chocolate instead of frosting. In my pictures, the cakes I used it on were the yellow cake with the chocolate Jayhawk mascot, the Black Jack cake--the cards were chocolate--and I also use it for detailing on some things, like the guitar next to the guy in the recliner in my pictures.

It isn't as easy to use it for a border, but for piping pictures or names, it works well.

One thing: if you don't refrigerate or freeze for a bit after you are done, the chocolate is weak and breaks. It will be stronger and stay put together better if you chill it. This is mostly for the transfer method--if you want to pipe on fondant, you might want it to be more flexible.

I've used it for "pop up" decorations on a book cake, which worked splendidly. You can absolutely pipe with candy melts, but keep in mind that you're not going to get much in the way of star shapes or shells or the like -- you are pretty much limited to plain rounded piping. Also, I probably wouldn't try to pipe directly onto buttercream. Use a transfer method instead. (Pipe onto a sheet of waxed paper, chill to set, then move the firm piped decoration onto the cake. If it's not too fragile, you can pick it up and use it right-side-up so you keep the rounded shape, or you can flip the waxed paper over onto the cake and put the flat back side up, like a FBCT.) Piping directly onto a fondant covered cake might work, though.