I had a brainwave when I bought a bunch of those cute little RiD Minicons - the tiny armour add-ons are on sprues shaped like faction symbols...
I cut out and smoothed the insides of the frame with a file, and mounted the frame on a thin piece of styrene. Then I made a frame on the back to house a rare earth magnet.
I made a number of mounting pieces with the right size peg (cut from junker bots) and placed rare earth magnets inside those. The mounting pieces can then be placed on the figure and the shield moved around wherever you want it.
Only thing I'm not happy with is that because of the placement of the peg holes on the figure's arms, the shield only goes on the back or front of the forearm rather than the side. I will keep work-shopping possible solutions, I think I can work out a system that mounts on the front of the arm but places the shield on the side using parts form a Kreo set.
The frame and back of the shield is colour matched to both Hasbro and Takara Fort Max.
Here's another one I did (slightly alternate design, since the "energy" effects were done freestyle)... and yes, I plan on doing a bunch more and will likely be putting them up for sale on the boards here sometime soon (please don't PM me yet!).
Here's the mounting system:
And here is the first one I did, a Deception one that will go with the Metrotitan custom I did. I hope that I can make more 'Con ones when Trypticon comes out.
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