I send decorated Christmas cookies out all the time (see my avatar). I pick out a sturdy box or ziplock type container (the straight ones), line the bottom with non stick foil. I arrange the cookies so they are packed in fairly tightly. I usually have different shapes so it's like putting together a jigsaw puzzle. I try to leave space as possible between cookies. I put another piece of non stick foil (non stick side down so any sprinkles, sugar, etc doesn't com off) and keep layering, I wrap the whole thing in bubble wrap or scrap paper. Then it goes into a bigger box with whatever packing materials are around (usually there is plenty at my house after Christmas!) such as bubble wrap, those large air bubbles (thank you Amazon) packing peanuts, etc. I mail out priority mail. In all the years I've been doing this my relatives always wonder how I pack them so well they arrive with no broken ones.