The top lip where the cover goes was edge banded with White Oak veneer. Prior to the placement of the veneer the whole case was sealed with sanding sealer as recommended by others. The bottom of the top baffle (if that's the right term) will be lined with Norez and the sides will be lined with felt as recommended by Danny.
The bottom is still off and will not be veneered since it has the same footprint as the top of the speaker stand. I'm toying with the idea of just screwing the bottom in since the fit is so tight and the Norez will seal the perimeter. Also, the speaker case will be bolted to the speaker stand. That way I have another way of access the crossover if needed. I don't think that will be a problem, but others would know.
They are looking good man
You could probably get away with screwing in the base, especially being it sits in a rabbet that goes around the entire perimeter so it will be pressed up against a surface.
The original X-Stadik's had a removable bottom plate as well and they were a sealed speaker for the 2 M165's, it was done in a very similar way