I may never put a finish on it. I don't really care that much about how it looks. I'm a function over form kind of guy, 99% of the time
I'm a little bit more finished than you (many people say I have an "industrial vibe") but nowhere near what my friend Tim did (he's just finishing up now; took over a year, his CNC machine sitting there).
He built his enclosure as FURNITURE with FURNITURE QUALITY. Real 2x4. Hardwood ones. Hardwood plywood (all layers). Screws. Seals on doors. Fine, multilayer finish - stain and sealer.
He designed custom dual pain windows (better sound suppression), diverter manifolds for the inlet ports, custom fittings for cable entry, custom LED spot lights (dimmable, of course), custom hard side ducting, custom dust head and attachments. The list just goes on.
It is so total overkill in my book... but it is gorgeous! He had so much fun building it I couldn't tell him to stop.
How about door seals?