Speakers and glue......

Look for a birch plywood cabinet. MDF or HDF will exsorbe mosture and mold just loves to grow on it. I had a scrap pile with MDF HDF some baltic ply. Had a bit of a water problem it got wet. I pulled it up to clean 2 days later and mold had already completely covered the HDF MDF. The ply was still well formed no mold the MDF HDF looked like a puffed sponge.

can't u order a dehumidifier from Walmart,Target or go on Ebay?

Your not going to want to run a dehumidifier for the 9 months of the year you're not there.

You should contact a manufacturer that will make a speaker for you bsed on your needs. I know of Tekton Design who would make you any configuration using the wood of your choice.

Quick question. I'm very interested in vacationing in Brazil for maybe 12 days or so. If I were interested in a vacation based around seeing live music, could you recommend a city? I know the country is as big as the U.S. and you pretty much have to fly if you want to cover the country because there's not much for trains, so I was hoping for a place that would offer some interesting sights fairly close by but also a very lively music scene. I'd plan on doing this just about one year from now, and hopefully getting a chance to see one of the all time greats like Milton Nascimento, Lo Borges, Jorge Ben etc.

Why not just buy outdoor speakers? Unless this is going to be used for critical listening, there are tons of manufacturers that make speakers that are salt and fog resistant and made to be outside, so the humidity inside would do nothing to them.

B&W XT
Vienna SCHÖNBERG

seems like they are mostly metal. I also recall that there were some Lucite or acrylic models out there. I recall seeing some show report that had a clear glass or plastic cabinet with only electronics and drivers installed. that should work a treat as well. bit of Windex and bang-zoom!