
To learn more about angklung, how it is made, and other pertinent information, you can read this Wikipedia article and/or visit the Angklung Web Institute site.
Although the angklung can theoretically be made from any bamboo, it is best made from two particular types of bamboo, i.e. the black bamboo (the Sundanese people call it "awi wulung") like the one in the bottom photo and the white bamboo or "awi temen".