Building frames is not particularly difficult. Especially your average photo frame. The difficult part is choosing the right frame for the image, unless you just stick to boring old black
I make frames for a living and although I have known framers stick images to backboards, I personally do not, preffering the more reversible method of attaching the image to the top edge of the mount.
Despite this, the dimensions of the backboard would usually be the same as the outer dimensions of the mount, so whatever way you look at it swapping images between frames need not be that difficult.