Could make some nice bottoms the same way. Iv'e got a sawmill and built most of my hives out of white oak and ash. I run gable end lids though. Wish I could get my hands on some cedar but it's not to common around here anymore. Nice job on the lids, the glue joint bit is sweet I need to get one of those.
Just about anything you want to use would work; I've even made some by just butt jointing as well. The most important thing is to get good tight seams and as much glue surface as possible. You can make them as fancy or plain jane as you like.
