After reading another thread, I eralized you might be asking about a carrying case, not the body shell of the radio itself.
You can find alimunim pistol cases with the foam, but the foam will not be precut to fit your 4PK. This is where you will have to bust out the magic marker, trace teh outline of your 4PK on th foam, and bust out a box cutter knife with at least 4inches of blade to cut it. I did this for my 3PK and still have that pistol case for my radios. It is actually much more durable than even the Futabal alum pistol case.
Check out this other thread concerning pistol cases for radios:
http://www.rcuniverse.com/forum/m_7473123/tm.htm