The Dan Bao is a traditional vietnamese monochord instrument. Before going to Vietnam I had a look on wikipedia to know which kind of instrument I could find there. The dan bao was one of the most unique, so I started to look on internet for some music shop in the cities we would have been visited. It was really an hard task! I found something that could be a music shop in Can Tho and, when I was there, we asked a motor driver to bring us there. The place I was looking for was located in a very traditional part of the city, very far from "turistic" places. But the "shop" turned out to be instead a music school, and obviously there were no dan bao on sale. Using a very simple english and some hand gesture, we tried to talk to some students, asking where we could find a music instrument shop. We finally understood where to go and we succedeed in finding the store.
The dan bao has a very very very very quiet sound: you basically play harmonics on it. The one I bought had a built-in pick-up but it was very noisy. So i managed to built a stand for a standard guitar pick using my old LEGO, and this solution worked quite well.