elastiPl8 - Mask Elastic Kit
With the shortages of elastic, buildPl8 has created "elastiPl8", mask elastic sold in a kit that fits one Montana Mask. Cut it in half and you have elastic for two loops.
elastiPl8 is elastic made from Thermoplastic Polyurethane. It has 95A shore hardness and can stretch extremely long while retaining it's original shape.