whatever you buy, get at least two of, that way when one needs washing you can put the clean one so you can rotate them. can find some nice things at dollar stores like baskets and stuff. if you can sew then you'll save a ton of money on hammocks
here are some things in my cage
https://www.amazon.com/gp/product/B08TZWV8HX/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B003TTY3UC/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B08ZSFD3BS/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
those are BIG baskets...fit normal sized paper, small baskets will work but these give much more room for multiple rats to snuggie
https://www.amazon.com/gp/product/B013KSVH1E/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B08RYWQ4PG/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B07W1Z3G55/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1
i recommend getting a bonding scarf, i got mine on etsy. you pop them in then relax on the couch or something. it gives them a safe spot while still being on you, its whole purpose is to speed up the bonding process. if they want to chill inside it, great, if they want to explore, great too.
also my biggest advice is to figure out your cleaning schedule and stick to it like glue, keeping a strict cleaning regime will go a long way into keeping your squishy beans happy and healthy
amazon and esty both have good things though etsy is more expensive but nicer stuff. i'll link you some stuff in my cage
https://www.amazon.com/gp/product/B08RYWQ4PG/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B003TTY3UC/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B016E1QHVY/ref=ppx_yo_dt_b_asin_title_o07_s01?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B08TZWV8HX/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B08Z7Y5168/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B08ZSFD3BS/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B013KSVH1E/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B07W1Z3G55/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B08ZSFD3BS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
i have lots of those in my cages. ziptied around the sides of the cages to make extra areas to chill, eat, and sleep and they're big enough for several beans to squish together