Sorry I didn’t find this link in time for you, but it might help if you decide to do any more. RBK used to be on this site, and he posted a link to some lovely photos of a home-made frame jig here:
Sorry I didn’t find this link in time for you, but it might help if you decide to do any more. RBK used to be on this site, and he posted a link to some lovely photos of a home-made frame jig here: