You will need: a disposable wooden chopstick, an old terry cloth towel, two or more ordinary rubber bands (or one large, thick rubber band as shown), water.
Cut a square piece (about 8 cm x 8 cm) out of the towel. Moisten it with water. Fold it into a triangle. Place the narrower end of the chopstick on the middle of the long edge of the folded triangle. Fold the left edge of the triangle diagonally over the stick.
Press down on the covered stick, rolling it tightly towards the right edge to make a firm, pointed tip at the end. Wrap tightly with the rubber band(s) to keep the towel in place.
Dip the towel brush into your bottle of sumi ink and draw the contour of your chosen image. To apply color, use a different (clean) towel brush, or a regular etegami brush. I used a regular brush for color.
After some practice, you may find a better way to make your own towel brush. If so, please share your ideas with me. I seem to have gone as far as I can with this method. The coarseness of the lines is intriguing, and I hope to come back to it after a good long break.