Below are pictures of of the picture frame doors you asked about. The pictures are easily changable. The front pane is thin plexigalss. The backing behind the picture is a thin, springy, copper clad composite product that I found at a salvage shop. The "glass", picture, and backing all sit in a saw kerf grove. As you are working with oil painting
, that will affect how you mount them in the frames I suspect. I assume you are painting
on canvas board ??? which is ~ 1/8 thick. My design for the back of the frames may not exactly work for you. My design is based on the flexible nature of the printed photo and flexibilityof the backing sheet. I'm sure it is doable though with a bit of creative thought.
If you want more pictures of anything in particular I'll post them for you.
Dave & Diane