Sorry, maybe in my attempt at brevity, I didn't explain this well enough. My idea is to have a box, and the box would contain perhaps 10 sets of triptychs. The viewer would open the box and take out the images and then, yes, unfold them. I'm inspired here by Japanese prints. I'm not sure I want to get too ornamental, like putting some print backing on each triptych. Too precious. Just a plain paper (or matt board) backing would be fine. But I don't want tape to be visible from the back.
I did a prototype a while back just gluing the images on watercolor paper and then using a bone folder to make a fold in the paper. That seemed to work okay, but the budget photo glue stick obviously won't last. I don't have experience with dry mounting, and I'm wondering if it would work on watercolor paper.
Thanks again for the answers.
E