{ I'm not sure if someone had told you already, but it's really easy to make one. c: If you can't make a Stamp Base, I suggest going on DeviantArt and searching up "Stamp Base/Template", or you could also search "-Put size here- Stamp Base", and there's a wide variety of them that you can use off-site, as long as you credit them and stuff.
And it's really easy to color most of them in, if they're white, because you can easily go to MS Paint and color it in from there, but Photo-Shop and Gimp are far more better than paint, of course, because you can use layers and such. c:
On topic; I actually didn't know I had a few other Rares from this year that came in a litter, but are in medium demand. o.o I should take a look at my pets more often...If I ever unlocked some.
I can only wonder what it's like to have an August or a July Lion...