Treebeard might not have recognized this tree-like figure as a fellow Ent, but CGI only works in movies, not Halloween costumes. Most people complimented Al on the excellent tree costume – somewhat to his dismay, as no one seemed to recognize that he was a tree-person, not a tree.
I looked at pictures I found online of Ent costumes other people had made, and among the relatively few I found, there was a wide variety in how people went about it. I even looked on sites that sell costumes of characters from Lord of the Rings, and there weren’t any Ent costumes (not that I could have afforded to buy one – I was just looking for ideas).
Fortunately it’s not too hard to make a costume that most people will recognize as a tree, even if I couldn’t find a way to make it look more Ent-ish. I suppose a couple of young Hobbits perched on the Ent’s shoulders might have helped, but making a recognizable Hobbit figure would probably have been at least as difficult as making a recognizable Ent.