I have received fabric and clothing in that really heavy plastic bag stuff. Like a envelope. but this was wrapped under the paper to keep it clean. It wasn't opened, it was rubbed open because it was a corner. a rough trip from Canada.
anyway, i know better than to ever say never, but if i request a swatch and it is heavy enough for a kilt; next time i would request a box. I sure they would help me out if i asked.