You can purchase Mylar from Julie Hall Designs, click the link below and will find explanations and freebies.
Hugs, Lidia

Thanks for the question.... I didn't know what mylar was either.

Sewco sewing centre in Brisbane has Mylar. Hugs Joyce

Punch with Judy has some, I see. Creek creations, as well. I also know someone who sells via Ebay.

Mylar looks like a sheet of cellophane and can make embroidery shine. If you are adding it to your designs crusning it in your hand before you add it to your hoop helps it to give off more colour and shine,. It is good added to Free Standing Lace Hugs Joyce

Great question I wondered what mylar was and if you could get it in Australia, lots of replies

I buy mine from Nancy;s notions. A pack of all the colors 5 sheets of each color cost about 35 dollars. You can but the colors individually too. Suzanne