Durable
Portable
Easy to build
Just add bed sheets for endless fun
geometrically precise solid plastic balls and reinforced sticks
See: https://www.amazon.ca/Everest-CF1-Crazy-Forts/dp/B001DNHYC0/ref=sr_1_1/151-434-639?ie=UTF8&qid=93&sr=8-1&keywords=crazy+forts
retails for $50-70