That looks like like an emulsion transfer or lift. http://www.polaroid.com/ has info. I've had a go with 5 x 4. Other than a polaroid back, a tray of very hot water and something to float the emulsion onto I don't think you need much else. It's a bit hit and miss though but can give unique and stunning images. Certainly well worth a pop. I'd try with 5 x 4 first, it's expensive.