Just seeing this now, but it seems like question was answered by
@skig (btw fabulous photos of the ponies!)
The project was created by myself and @wingsofmasquerade (Em -not sure if shes on the MLPTP currently?). There are also ollectors who do help with design, and other works such as @wysteria. I can't remember the other collectors user names on here or the arena, but there's 9 of us in total at the moment helping getting these ponies to collectors.
As for designs, majority of the ones created I have envisioned myself and pass the idea along.. But they are all group effort and decided as a whole what will go and what doesn't.
For more information, the facebook group has a pinned post in the announcements about the project. I also have made a video talking about it, that I will bump up in the feeds for members to see.