The wide size is important because marmosets live in trees. If possible create outdoor enclosures with a heated indoor cage. They can spend many hours exploring their home. Many marmosets, like all monkeys, show signs of boredom in captivity. So, use a lot of different items in their home.
Toys Change their environment from time to time.
You must clean indoor cages every week. Marmosets scentmark their cage constantly, therefore it is very important that you don't sterialize their cage at once. Clean the nestbox and the cage at different times. Use a mild desinfectant to clean their cage. For outdoor cages, don't forget to provide some shade in the summertime.