Think this might be my next upgrade project. Trying to keep my filament dry while printing. 200mm x 250mm acrylic tube is only £19 on the bay, will get both sides out of that. printing the ends. It will have desiccant in pockets in the ends to keep it dry inside. Filament exiting through a sponge to clean and keep it as dry inside as possible.
Nice. Somebody had posted the idea of using a small binder clip with sponge inside of it, I use that at work, works nicely. Let us know how our dryer box works, I may steal that as well 
model is shared to the sketchup warehouse if anyone wants to play with it. just search replicator.
I want one.
Very well thought out!