One such prototype was an unknown accessory that Galaxy Shuttle was sporting.
A shield and base attachment? I'd never heard of this. My interest was piqued.
The shield acts as its namesake when Galaxy Shuttle is in robot mode, and attaches in base mode to form a Micromaster launcher. Thought to have originally been intended for release with the Galaxy Shuttle toy itself, it's possible that it could have been marketed separately with its own Micromaster. Either way, it's a very cool piece that sadly never saw production.
This is a resin hardcopy prototype that, oddly, has a copyright. A simple "c TAKARA" is located on the underside of the shield. A very unusual trait for a prototype of an early-stage.
The shield is surprisingly large and in addition to the features previously highlighted in the Generations Deluxe book, it strongly resembles a sort-of space cruiser. Perhaps further fuel for speculation that it was to be marketed separately.
Monzo has kindly commented in this post with the following information:
"Autobase Aichi has an article on this particular part, but it's buried on the site:
According to a Japanese-speaking friend, the article says that the shield part was given away at Japanese stores (not stated which ones) as the "MicroTF Launcher" in the summer of 1990. However, its connection to Galaxy Shuttle was unstated, and the give-away received no advertising. The Autobot/Cybertron symbol sticker was not included with the part, but was added by its owner.
So... apparently it was released, but in a very limited fashion."
This is interesting and seems to make sense, given that the example shown in the link which Monzo provided does indeed appear to be further along in production. It has additional, more crisp detail on the underside compared to the pre-production example pictured here on RobotPoints.
A more rough appearance is perfectly normal for a hardcopy though, but one needs to again question the copyright. The thought occurred that the shield on RobotPoints could possibly be a copy from a reverse-engineered mould of an original store exclusive. There are two signs to refute this however. Provenance is not fool-proof, but is oftentimes the key to denoting authenticity. With this in mind, the first sign is that the original owner can assuredly claim legitimacy. Secondly the lack of detail and general condition of the underside does not a reproduction make. If those were the resulting side-effects of creating a second generation copy; then there would be no (extremely fine and crisp I may add) copyright. It would have been lost in the process with the rest of the detail.
Still, the presence of a copyright on any resin hardcopy continues to bewilder, and the notion of release, however limited, is certainly a lesser-known fact about this unusual piece, now known as the "MicroTF" launcher!
Thanks to the Mapes brothers, of TF@TM (transformertoys.co.uk) for the Generations Deluxe book scans.