How to change a film SLR camera into a digital SLR camera?

If you have a wide range of contacts, maybe you can buy a trial product called "silicone sheet" in Chinese, and put it in the camera film compartment like film, so you can shoot digital images. If it is a medium format SLR, it will be much simpler. Just buy a back pack, "Freescale 1", "Litu" and so on. If you want to graft ordinary digital cameras and film SLR onto digital SLR, the difficulty will be given up directly, because