plastics modeling

Check with NASCO in Ft. Atkinson, WI. Here is one material: http://www.enasco.com/ProductDetail.do?sku=9718642. I didn't find any shipping restrictions in a quick look, but they can certainly tell you what can, or cannot, be sent by air. They have an extensive line of casting materials, mold materials, etc., and may be able to offer advice on how to proceed. This is from the eNASCO catalog on arts & crafts: Arts & Crafts Materials - Sculpture/Modeling - Mold Making & Casting. Depending upon where you are, they also mention having local distribution, which might eliminate the need for air shipment.