I was having the hardest time trying to get Blackjack to stay in place. Plus when he was in there I wasn't really a fan of the horizontal attachment. So I decided to print up these. After some trial and error and some alternate transformations my (soon to have his limbs) Menasor and Ultra Prime look like this.
I made a smaller adapter for hooking in Blackjack or the upcoming Rodimus. I can't wait for legends Skywarp, I think it will look perfect in Menasor's chest.
The other pics are what the adapters look like when attached.
I would like to hear what others have done for chest pieces and which bots you think would look good there.
I'm sticking these up on shapeways in case any other collectors want a set.
http://shpws.me/GyxB