Cut side with grove for bottom:
Cutting grove that fits corrugated cardboard for doing mite counts and closing off bottom in winter. I prefer to use corrugated plastic sign material as it holds up better than cardboard.
I use poultry staples to attach the screen to the bottom rather than doing anything fancy.
The bottom board fits the side like this:
The wood I used on this one is a mix of bandsawn pine and poplar. I air dried it in a shed for about 6 months before using it. It is un-planed full 1X lumber.