Gorilla glue (not wood glue) and then screw with 5x80mm self cutting thread (no need for pilot holes) before it dries.
I just trim when it has set and fill with pollyfilla wood flex then paint.
I use these frames, they fit together to make a Dadant super frame
https://www.icko-apiculture.com/cadron-bois-miniplus-emboittable.html?refSrc=4938&nosto=nosto-page-product3