Cool I see what are talking about.
The issue you are going to run into with the adapters not being sealed is moisture as mdf is basically really nice cardboard. It will whick up moisture, swell, and degrade over time. More than likely not for a while however this will be an issue.
I think I either hit Steve up about this or it was tossed around, they dont come sealed as it gives the consumer the ability to coat how they want. Paint, resin, glass, etc.