UPDATE: I don't know if I will put in effort to fix the leftover paint marks. Since you have to put down a base coat anyway, it's not much of a hindrance, but it is kind of... ugly. I'm finding that in order to really fix it, I'll have to re-do all the coding, which will take many hours, with all the colors I've got. But I know it's annoying to constantly refresh the page, so in the meantime, there is at least a functioning back button for you to use; it just won't give you a clean start.
I finally made something with it. ^^ [link]
Since I get a lot of questions in regards to adoptables, I'm putting it in the description: PLEASE DO NOT use creatures created in this particular Maker for adoptables. You may, however, use the game to design creatures and then redraw them for those purposes; in other words, just so long as you're not taking screenshots directly from the game and using them for adoptables, that's fine.
Also, it is fine (and encouraged!) for you to upload screenshots of your creations to your deviantArt gallery, just so long as you credit me and link back to this page.