I am really nervous about attaching my candy melt shells my fondant cake because the candy has shortening in it and I thought RI wouldnt work. I want a clean look so I was thinking using melted candy melts to attach would not look so clean.
Any ideas would be fantastic and always appreciated!

For small, light things I've used buttercream. I suppose RI could work, too.

For heavier items, I use melted chocolate.

Rae

Certainly melted choco will do the job. So will b'cream or royal. NO need to worry about the tiny bit of shortening in the shells/candy w/royal!

After my chocolate shapes dry, I add a little chocolate spike to the back. Then you can use whatever you want to stick it on and the spike goes in the cake and helps stabalize the chocolate decoration.