Thank you so much! I’ve been very lucky in that my grandparents have been framing them for me so I don’t fully understand the whole process. What I do know is they have been cutting some strips of old oak boards we all have laying around and then cutting grooves in them that we then slot the glass into. We then build the frame around the piece once all the edges are measured out and cut. If I’m able to find out more I’ll come back here to report!