Mine love feathers as well
we picked up a feather boa at a dollar store. Feather dusters work well also and are usually not dyed. Cat Teasers with feathers on the tip are great to run along the outside of the cage, just make sure it's cat nip free
cat nip is toxic I've not had any problems with dyed feathers but some folks suggest to not leave the feathers in the cage over night. I usually just give them a couple feathers in the cage and they always end up in their sleeping pouch. The feather boa I use doesn't get put in the cage either, the feathers are held onto boa's with several strands of ropes/twine twisted together that nails could get stuck in.
As for natural feathers it's also not suggested to just go pick up feathers outside from wild animals to avoid bringing
lice or mites to your gliders. Craft store feathers are usually sterilized.
If you raise chickens or other birds you can sterilize the feathers yourself by soaking them very carefully in some warm sudsy water with dishwashing detergent, rinse, then let them air dry on a paper towel. Then stick them in the freezer for a couple of weeks to kill any mites that may be there.