Well I've been talking with Silv about this I figured I would just put up what I made in a new thread and see if anyone has a better idea.
I wanted to quiet down my 3500W generator that I picked up from Tractor Supply for $300; its not terribly loud as it is, but its not a Honda. I was reading about enclosures and figured I'd put a small amount of effort into one and see if it helped at all.
I just measured my genny, added a foot everywhere and then cut plywood. I fastened it together with some L shaped brackets from Lowe's, put some handles on top and a coat of deck stain on the exterior. Then I got some carpet padding that I think is for berber, its not as "foamy" and feels more dense. I just took a staple gun and stapled the hell out of it on the inside. I left the one side open and point the exhaust at an angle out the open end.
Pics:
It makes a difference for sure, I heard everything else at the track day but not my genny, I had to walk towards it to make sure it was still running, but the pits were loud that day. Wish I had a db meter. More insulation or padding would help, but I didn't think a staple would reach all the way through two layers. The number one drawback is its size, if I didn't have a truck this thing wouldn't be an option because of how big it is, if you could make a foldable one it would be much easier to transport. As it is, it does what I need it to and was only a 1 beer job.
Nice setup though.