Where Can I Get Custom Made Foam for Speaker Box?

I bought a can of "Great Stuff" at Home Depot. It is a liquid that is sprayed out of an aerosol can. The liquid rapidly expands and then hardens. I used it to seal around some pipe openings in the garage wall -- just spray the stuff into the opening and it seals against insects and rodents.

Here's a video that gives an idea of how this stuff behaves:

http://www.youtube.com/watch?v=uloK98jMTGY

It's available at other retailers, too, but here is Home Depot's page on it:

http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?productId=100003351&storeId=10051&langId=-1&catalogId=10053&ci_sku=100003351&ci_kw={keyword}&kwd={keyword}&cm_mmc=shopping-_-googleads-_-pla-_-100003351&ci_gpa=pla#.URGCwWdZMa8

Why don't you just pack it real tight with bubble wrap or rolled up newspappers? What is your concern? If you pack tight speaker will not move.

What Jameswei wrote. I would add perhaps buy some scrap solid foam for the outer portion. (and the bottom) then perhaps wrap the speaker in thin plastic wrap, place it in the box on the foam bottom, with major areas filled with solid scrap foam, then spray in the can filler. it will adhere to the foam, and the plastic.
When it is dry, take the speaker out,'It will have the shaped foam spray for you to ship the speaker in. The plasitc left in place on the foam will even help protect the finish.