I've posted this info before, but it was requested again, so since I was taking some new photos, this seemed like the time to do it. I use plastic tubes that I get from cheap toys or candy, or sale cheap cosmetics. I've collected various sizes over the years so I can put my dolls at different lengths away from the background. I use white sticky putty, or earthquake putty to hold the tube on the background, & then I lean the doll against it.
This is the putty & tube


This is my background setup with a tube attached. Look closely at the bottom right corner of the "painting" it's a little hard to see.


And here's Zoe in the finished photos
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You can use this with a real diorama too, put the tube on furniture or walls to get the doll to stand further away from things.