I want to do something like this on a cake...would you use chocolate clay or just melted chocolate chips or Wilton wafers. Thanks.

Looks like molded candy plaques...just use melted candy melts or "almond bark". You can mold them for perfect size...or if in a pinch just pour the chocolate onto wax paper and spread out evenly....then when its about room temp and almost hard (but still a little soft) cut through it and then let harden completely.

I think the molds will make it look nicer though..like a plaque or candy bar mold. Actually they kinda look like the backside of a boughten candy bar!