Begin with a diamond shape that has rounded edges. It needs to be it about 9 inches (22.86 centimeters) high and 8 inches (20.32 centimeters) wide. Cut the template out when you are done. Make the top and bottom corners a little wider. They should be about 2½ inches (6.35 centimeters) wide. This will be the exterior of your cloth pad, so choose something that you like. You can use patterned fabric or a solid color. You can even use a pattern for one side, and a solid color for the other. You can also use cotton fabric instead of flannel. Check out the quilting and calico section of your local fabric store for lots of colorful options! Pin the two pieces together first, with the right sides facing in. Sew around the piece using a ¼-inch (0.64-centimeter) seam allowance. You do not need to leave a gap for turning because you will be cutting a slit into it. Make sure that you are only cutting through one layer of fabric, not both. Position the slit right in the middle. It only needs to be a few inches/centimeters tall. Consider cutting notches into the curved corners of the pad. This will help reduce bulk. Use your fingers to push the corners of the pad through the slit that you cut. If the edges/corners didn't turn out all, push them out with a pencil or knitting needle. Press the pad base with a hot iron using the cotton setting. You can use a matching thread color or a contrasting one. You can even use a zigzag stitch to make it look more interesting. Backstitch at the start and end of your sewing, then trim the excess threads of as close to the fabric as you can.

TL;DR in Indonesian:
Buat pola pada sebuah karton. Gunakan pola untuk membentuk dua lembar kain katun flanel. Jahit kedua bagian kain dengan sisi depan saling berhadapan di sebelah dalam. Buat sayatan vertikal di tengah kain. Balik sisi depan melalui sayatan di tengah kain. Jahit keliling bagian atas alas pembalut.