This creative technique uses a vacuum cleaner as a sunflower sheller.
I raise sunflower seeds for my granola cereal. I use a paint stripper on my electric drill to strip the seeds off the heads onto a large piece of plastic. Then I run the seeds through a Kirby upright vacuum cleaner to remove the shells. (To control the flow of the seeds to be shelled, I take off the bag and use a vacuum hose with plastic tape over half of the end.) The hose was attached in the normal way. It works great: Out of two bushels, only a few meats were cracked and only a few seeds didn't shell out.
The nut meats pile up about 20 inches beyond the exhaust. The larger chaff carries further. To remove the fine chaff, I put the meats in a pail of water and run water into it, until it overflows. The light chaff comes to the top and spills over the top with the additional water. I drain the water off and put the damp meats on a cookie sheet in a 230degree oven until they are dry.