Here's my DIY compressor cabinet I built back in May, 2012 and still holding up fine. If you'd like more details let me know.
How about a BOM (Bill of Materials) and a write up on how you built it? Or a link to it if it's on here somewhere?
Is there a screen over the fan on the bottom?
Looks good!!!
Have you ever had snow get high enough to cause air flow problems thru the cabinet in the winter?
I like the manifold, but wouldn't hang it that way. Fix mount the manifold and run hose from the compressor to the manifold.
One thing you guy's should consider is from your branch circuit protection (main circuit breaker in your breaker box), is to toss in device protection at it's level. Rather than feeding 15 amps into something that will only eat 3 amps on a good day, fatten up his maximum meals he can eat 125% with an appropriate Fuse or Circuit Breaker. Yep, overeating amps has a tendency to cause that burned electrical smell.
Just have a boring Grey box here for the outdoor rig.