I don’t think it’s that hard, but it is a commitment (I guess the local HomeDepot/Lowes is ‘your friend’:-)
The one my father-in-law had looked like about 2:27 in this video, but a lot smaller and with a chimney. Wasn’t fancy, but worked:
https://www.youtube.com/watch?v=hjyVk7ciVRI
-JT
The problem isn’t building one. The problem here is HAVING one. Some dumb rule.