Mystery Item

We're cleaning out the house we grew up in. Neither of us are living in the area, so there isn't much that makes sense for us to do other than sell it. Boy, Dad sure did do a lot of modifications. I wonder how many will turn out to be to code. We're also coming across some mysteries like this one.

What's it?

I have vague memories of him building it, but no idea what it was for. One possibility was that it was some sort of holder to help in the assembly of the hexagonal hurricane lanterns that he was fond of building.

Seems unlikely though. The lanterns didn't vary in size, so wouldn't he have built it to be an exact fit? The most likely use to me is that it was something for Mom to wind yarn on so that it could unwind easily while you're knitting. I can just about call up the memory of Mom knitting with this thing mounted to one side, but that is just as likely to be a “recovered” memory. If that's it, then I bet it didn't work that well, since it was banished back to the wood shop.  

Anyway, that's my best guess. Anyone else have an idea?