I collec the shells in a zip lock bag, on fridays i bake them at 350 for 10 minutes then place the shells between to sheet of wax paper and use a rolling pin to crush em up all nice. I then place the crushed shell into a empty coffee can for later use. I apply crushed shell to the feed every saturday or if i notice the shells getting thinner than usual. i have stopped oyster shell all together, replaced by egg shell.