The Chu-Ko-Nu is a 2,400-year-old Chinese repeating crossbow featuring a 10-shot magazine. It was a marvel of mechanical design that was still in use up until the era of gunpowder weapons. Make: Online reader BjÃ¸rn sent in a link to maker Leong Kit Meng’s recreation of the Cho-Ko-Nu. The photos are nice, but the instructions and plans are fairly non-existent at least on this page. I found another site with more detailed instructions if you want to make your own.