If I lived someplace warm year round where I could leave it outside, I'd definitely give it a try, they look like fun. I just wouldn't have the space to bring anything that big inside and have it be near a window. I did some digging and found these interesting sites though:
https://everydaybest.com/how-t...
You can buy ready-made forms filled with moss here:
https://www.hendersongardensup...
Nessie was my favorite (but ouch! the price!), and that got me wondering if you couldn't shape your own out of chicken wire maybe and fill it with the spaghnum moss? I've got a Nessie-type banner in queue for someday from a park that looks like they could have ordered from here. And the turtle on Page 4 has me rethinking "do I have room?"