I have 2 pouches in each of my cages, and my pairs will only occasionally sleep separately. They usually use one pouch for quite a while and then when they switch to the clean pouch I replace the stinky one. I have tried different shaped pouches, since I like to sew. They are curious about the odd shapes I have made, but it really doesn't seem to matter to them. They don't seem to like the honeycomb hammock for sleeping, though. I made a cone shaped and a Christmas stocking shaped and I was sorry that they liked them because with the small opening it was hard for me to get them out.
You really don't know what they will like until you try something.