Another good source for polyester is Ceconite. Just Google "Ceconite" to find several sources and also to see just what it is. I have used it (purchased from Spruce Specialties) and it is great. As to shrinkage, it sure does shrink with heat, so be sure to have a strong structure and be able to control the heat when you go to shrink it tight. Get the lightest weight, it comes in at least three different weights and the the two heaviest are to high for most models. Note: you have to supply the adhesive, nitrate dope works well.