150g light black cardboard is a kind of thick black cardboard, which can be bought in general art stores.
There is a special painting shop (table Chinese painting or calligraphy, etc.). ), you can also buy your own paste and cardboard and go back for mounting. The point is to brush the rivers and lakes flat, and draw a paste to make them flat.
Cardboard is cheap. 3-5 yuan can have a fully open. Paste, it is estimated to be cheaper.
It's more expensive to install in the store. But if you are a novice, I suggest you go to the store to frame it.