The printing press for example relies on a system where it uses metal letters to print a book, but in China wouldn't they need a lot of metal characters to print a single book in Chinese?
How did they adapted the printing press to the fact that Chinese has thousands of characters?
It did create problems, which was why woodblock printing ended up being more popular in China.
Movable type was originally made in clay and typeset on an iron plate coated in a resin paste. This was around the 1040s. Bi Sheng, the person credited with this invention, made up to twenty copies of each character, which you can imagine meant quite a lot of tiles. There were a couple of other reinventions of movable type during the Qing dynasty, in wood and in copper. For the Encyclopedia project in the 1720s, they used 250,000 type pieces. For the wooden system later in the 1770s the number was about the same.
Block printing has been around at least since the 9th century, and printing from paper rolls since the 7th. Before the Song period though, manuscripts tended to be copied by hand. Woodblock printing was by far the most preferred print method in China and Japan (don't know about Korea) until pretty recently, at least until the end of the 19th century.
Lothar Ledderose's book Ten Thousand Things: Module and Mass Production in Chinese Art has a whole chapter on printing that is really good. He actually traces printing back to bronze vessels and seals rather than just sticking with what we'd typically think of as full texts on paper or cloth.