How large are we talking medium sized ones I've cut the top off gallon jug or pop bottle and stuck slate tile into a piece of styrofoam and then go to lfs and have them give you a large livestock shipping bag and ask them if they can fill it with oxygen(also ask if they have a ³/4 inch cooler or 1inch cooler you can buy(if not buy one online at bait shop or hardware store),make sure to poke a few air holes in styrofoam cooler for air exchange and expansion ,after the bag is filled up ready to go and coral is nestled in piece of styrofoam and bag is filled up go to pet store get 2 72hour heat packs tape one to lid and one to bottom,double bag coral bag with garbage bag(helps with photosensitivity) then put in preferred filling(newspaper bubblewrap peanuts etc etc) then put it in a cardboard box;go to local FedEx or ups location if it's a sensitive lps or sps keep in contact with customer and see if they want it held at ups or FedEx location or sent to local airport for holding or straight up overnighted to house or business after that ask fedex or ups about appropriate labels(they will print them up for you) then they will throw your parcel on the scale, mark liquid, perishable and live animal they have special boxes(say this side up) pay for overnight shipping... they will take your package print you out a receipt, then contact customer with a picture of recipt and then send tracking #
For stony coral imo I dont like using containers if they're glued to a rock I pop em off and re glue to a large plug and stick in styrofoam when shipping to prevent inversion or bouncing around, if it's something super large like a chalice or monti or acro colony I would just double bag it and try to finagle it to the middle of container and put softies on the outside edges or corners if it's a single order for a large colony you can bag it like normal and then put in a few empty bags filled with saltwater to act as a cushion during shipping
Personally elegance wall type hammers and smooth skin acros haven't shipped well for me until I tried the second method which was recommended by nic Culver at eyecatching corals