be made of 用于能直接看出原材料的,如this chair is made of wood.椅子是木头做的.
be made in 指产于某地,如silk is made in China.丝绸产于中国.
be made by 指由制造者、制造方制造,如the software is made by Microsoft compeny 微软公司制造.
be made into的意思为"被制成为…".
This piece of wood will be made into a small bench. 这块木头将要被制成一个小凳.
扩展：be made from 用于制作加工时改变了原料的性质,如the paper is made from bamboo 纸是竹子做的.
希望这些对你有用!