If you want to make it avaliable for non-subscription users, you have to create two plz-accounts which can be put together to get your original stamp. Here's an example: Click on the image to get to the site and you'll see that this is a puzzle stamp made of two icons.
First icon: Second icon:
Basically, it's the same thing as creating two new acconts on deviantart.
As long as you rename it with ...plz it's allowed. Plz accounts are just for the purpose of the icon, nothing more. So they're pretty inactive. I honestly don't know what it means, I guess it's "please" for typing the name of the icon and the person who typed it wishes for the right icon to appear
Maybe you should turn the number of layers down to maybe 5 or 6. This way, it's easier to split. Also, each part of the big plz should be smaller than 15 KB.