A part of my purchases from M, these are very large cardstock prints done in traditional CMYK with some very unique algamations of early Gundam promotional art, some of which were made just for these proof of concepts. These implicitly came from a reference packet as shown in the final, which has either a serial number or product number at the time. This was on the plastic that these were initially stored in, which was heavily deteriorated.
Based on Yamamatsu's product line at the time, these often show up for sale attached to larger backing boards for their vintage gachapon-style candy vending machines. Some of these did not make the cut, primarily the piece of Hayato and Paolo Cassius, which is very mysterious. These were done from the earliest episodes to about episode 12 or so, as a Zanzibar class ship is shown albeit with different coloration, alongside Garma's Gaw carrier.
M told me distinctly that these were shopped around to toy and convenience stores and were given to someone who worked for Sunrise's advertisement/licensing department. These are 12 inches across horizontally and 9 inches vertically. There are possibly more out there, but I've yet to see them. Should I run across them, I'll acquire them and archive.