Materials: one outer layer of cloth, one inner layer of cloth, one piece of wire, two elastic straps, two cloth straps. 

(The video shows the HK Mask Kit, but you can make one yourself without a kit)

The size of the cloth will vary depending on the pattern you use.

You will need: chalk pen, tape measure, paper cutting scissors, cloth cutting scissors, thread cutting scissors, pins, pincushion.

If you have a sewing machine at home, you will be able to work more efficiently.

There are five free HK mask patterns for babies, children, teens, women, and men. (XXS, XS, S, M, and L.) Choose the pattern that fits your face.

The patterns can be downloaded from here.

The stencil must be the right way up, with the center of the mask on the right side of the stencil and the sides of the mask on the left side.

A 10cm scale is shown on the right end of the stencil, so confirm that there is no mistake in the scale when you printed the stencil by measuring it with a tape measure.

The outermost solid line on the pattern shows the outer edge of the outer fabric of the mask, and the thick dotted line shows the pattern for the inner fabric of the mask (slightly smaller than the outer fabric). The thin dotted line is a sewing guide for the seams. 

Any paper will work for the pattern. Print out two sheets of paper and cut along the lines of the outer and inner surfaces, preparing one sheet of paper for each layer.

Fold both the outer and inner fabrics in half so that the inside of the fabric is facing outward. Place the stencils on the fabric and fasten with pins. For the outer layer, cut around the outside of the pattern, and then make a notch in the area marked "notch hole". For the lining, cut around the thick dotted line and the cutting process is complete.

Sew the left and right halves of each layer together. First, with the fabric lining facing outward so the seam is on the inside of the mask, sew down the center of the mask, 1cm from the edge. When you're done sewing, reverse the fabric.

*Image: Wrong Side refers to the reverse, inner side of the fabric.

Next, fold a 1cm hem along the top edge of the outer fabric, with the lining of the fabric facing up. Sew as far as the first notch hole so as to secure the fold. Next, insert the wire into the notch hole and sew the rest of the fold.

Similarly, with the fabric lining facing up, fold a hem in the bottom edge of the fabric about 1 cm wide. Sew to the edge so that this fold is fixed, and the outer layer cloth sewing is complete.

Next, the inner fabric is sewn. Fold a 1cm hem in the top and bottom of the fabric, with the lining of the fabric facing up. Sew all the way to the edges to secure the hem.

Attach elastic to the outer surface of the outer fabric. Mark the position for the elastic at the ELASTIC PLACEMENT position shown on the pattern. Sew about 1 cm from the edge of the fabric.

*Image: Right Side refers to the outer surface of the cloth.

Place the outer and inner linings together so that they both face inwards, and sew the left and right sides together about 1 cm from the edge. Sew the elastic in place as above. Cut off the excess cloth at each end (about 0.5 cm). Then turn the mask the right way out.

Thread a string between the outer and inner fabric and secure it to the ends. Sew the two pieces of cloth together about 1 cm from the edge, so as not to sew the string.

Sew a small rectangle at the bottom of the mask, about 1 cm wide, so that the filter does not fall out from under the mask. Sew through both pieces of cloth. Next, sew both sides of the wire so that the wire at the top of the outer layer cloth does not slip out. Finally, tie a knot in both ends of the string, and the HK mask is complete.