If need be, you can replace the elastic with four 18" lengths of 1/8" cord or long sewn fabric strips. But clothes driers typically run at 140 F, so 150 F probably will not hurt the elastic.

My wife was burning little swaths of all her fabric pieces last night, to see what was natural and what was synthetic. Natural fabrics work better for catching droplets. They burn like paper. Synthetics burn more vigorously and leave little beads of melted plastic. She got some very simple mask patterns off the internet. I managed to print it out for her before I screwed up my printer. It pulled in the pulse oximeter cord, and I pulled it out. Now it says it has a paper jam, but it feeds paper perfectly.