Thanks. Right after I cut the dividers I remembered I needed to make my channel deeper and cut them tight enough to close that gap. You can see in my post above how I fixed that Oops.
I will have to figure out how to cover up those groves on the interior, that is a good point. I have a whole unit of beautiful Cedar decking I plan to use. This is just how it came-with the groves to prevent warping. I generally make my woodenware out of stuff I get from my friend at the cedar mill. Frequently he will give me or sell me shorts which work great for hives. My patterns usually are made from the least waste of this wood. Maybe fill them with dry pollen substitute in the fall.