A hakobi is a traditional type of brush that's used in Japanese woodblock printmaking 「木版画」to apply pigment to the block. You can order these but they're not too hard to make and the materials are super inexpensive. All you need is wooden chopsticks, string, bamboo sheath, and some tools. I made this hakobi following instructions from Tokyo based woodblock printmaker David Bull. Here's how mine came out:
Not bad for a first try. It took longer than I expected to separate the bamboo sheath fibers, I was probably banging that thing with a hammer for 30 minutes or more. It also made a mess in my kitchen, so maybe next time I make one of these I'll do it outside.