They are real sturdy and easy to put up. I just buy the panels and screw them together. The panels are chain link fencing. The bigger the cage the better. A cage can never be secured enough, don't underestimate the power of primates.
Monkeys can spend many hours exploring their home.
Try to use a lot of different items in their home. Droppings and excess food should be removed daily. Never use chicken wire. Don't forget that monkeys like capuchins are very strong animals where a chain link of appr 12 gauge strength should be used. A safety entrance to prevent monkeys from escaping is certainly not a luxury.