What I've seen and heard about are those cat tubes... Some macs like those things. (Fargo.) They are like hollow tree nests...
Mine don't.
I actually knew someone who made a macaw hollow tree out of one of those oak barrels. Got a full oak barrel (the kind they cut up and use for planters.) Cut a hole in it, draped a cargo net on either side of it, and attached a manzanita tree playstand to the top of it...
WHEN THE BIRD WASN'T LIVING ON IT, HE WAS LIVING INSIDE IT...
THERE'S A DIY IDEA FOR SOME CREATIVE PERSON...