Today, in the darkroom, complete darkness I placed a 4x5 sheet in the back of the Polaroid 150. Sure it's a one at a time deal, but I can't wait to develop and see what comes out and then leverage it to more suitable subjects from the minds eye.
I also use the Fuji FP-100c in my Mamiza RZ67 back. You MUST get the 3 1/4 size as the 4x5 will not fit.
I have a Instax for kicks. I'm super surprised of how good the images are. I do a few tricks, i.e., place the instax on "light" use the flash and shoot almost directly into the sun for max Saturation.
I too am looking forward to seeing what the project et. al. produces not only tomorrow but over the next several years.