Some of the early developed coins for the 30th Anniversary Series went through some design changes. Here is an example of an Engineering Pilot Luke Skywalker (Yavin Ceremony) with an early designed McQuarrie Stormtrooper coin. The bottom of the unproduced coin reads "Concept" at the bottom of the coin
and the final production coin reads "McQuarrie Concept". If you have any unproduced TAC coins, please post them!
I'd have to check old notes, but If I recall correctly, the coins were done as two ups. Dave mentioned that he had to do some additional work on most of them.