Its pretty easy to do yourself. Get as much meat out of the head and tail as you can without destroying it. Put back together and onto a board that you can pin the legs, head, tail etc etc the way you want it. Then inject Formaldahyde into body and joints and repeat until all dryed out. Then coat in a clear epoxy !

 Did it years ago without splitting the body from the head. Just injected all the joints with formaldehyde then pinned it how we wanted it. Put a foam block under the body to raise it up to the correct height. BEWARE when injecting the formaldehyde that the needle doesn't block up and the needle comes off the syringe. Wear safety goggles just in case as I spent a couple of worrying days in hospital when it did just that and sprayed into my eyes. All I could think of was if the formaldehyde dissolves the crayfish flesh what's it doing to my eyes. Fortunately I fell into the sea and it flushed my eyes sufficiently.