Just one more comment and then I will be quiet! LOL
We have found with Zach that the more texture you use in the fabric the better. Smooth is not the best choice. I don't know if you have any say in this but thought I would pass it along. My DD had me make a blanket with several differant textures in it and he runs his hands over them and it calms him. Satisfying the sensory needs is every bit as important to these kids as breathing and eating are.