@novid
Materials/resources needed:
Hot glue gun, glue sticks
1 X-treme EPDM rubber band.
3 black elastic straps (from discarded masks)
3 coffee-bag sealing wires (from discarded coffee bags!)
1 mask ear loop adjuster + crochet hook or bobby pin to install
1 black or dark colored pipe cleaner. 2/

@novid
Modifying the mask: Identify the top outside of the mask. Hot-glue one of the sealing wires over the installed nose wire and allow to dry. Tie one of the elastic strips between the ear loops so that the mask may be worn without looping around ears as a headband.
(At this point, I also coat the mask with a highly-saturated indirectly virucidal salt spray and allow to dry; but others may want to skip that part). /3

@novid
The mask brace: install the ear loop adjuster on the EDPM rubber band using a crochet hook or bobby pin. This will be the base of the brace. Bend one end over of each of the remaining sealing wires, and loop the pipe cleaner around each end, twisting close the loops to secure the sealing wires to the pipe cleaner. Tie the two remaining elastic strips into loops and secure on either side of the rubber band (the adjuster is south; the elastic loops are east & west). (cont.) /4

@novid
Bend over the remaining two ends of the sealing wires and hook the elastic strip loops onto them to form the complete brace. Adjust the tension of the brace both by modifying where the bends in the sealing wires are and/or by lengthening/shortening the ear loop adjuster. The top of the rubber band will stay around the hot-glued nose wire, and the base can be tucked beneath the chin at the adjuster. The brace and nose wire should sufficiently seal the mask. 5/end