I tried making onigiri from barley rather than rice and I was happy with the results. It's not that I don't like rice, but barley is much better for me because it helps lower cholesterol. I made the barley and followed the onigiri method where you wet your hands and form the onigiri that way, although I found I had to let the barley cool just a bit first. I found that it was sticky enough to hold together and it was also able to hold onto the nori. I didn't try stuffing them with anything but I'm sure it would have been possible.