One of Gutenberg's most radical ideas was to use a press for printing.
Presses had been around for a long time, but for other purposes.
It is often pointed out that Gutenberg came from a wine-producing
area of Germany and that he must have been very familiar with the
wine press.
The printing press was essential for making the whole process fast
and so, ultimately, commercially viable. Also compared with rubbing
it saved a lot of money, for one could use both sides of the paper.
It would not have been possible to use a press if Gutenberg had
not had a way of making his pieces of type exactly the same height.
We do not know how Gutenberg's press looked, but we do know that
the press was improved in the 1470s, enabling printing to be even
faster.
On the improvement to the printing press in the 1470s, see Lotte
Hellinga, 'Press and Text in the First Decades of Printing' in Libri
tipografi biblioteche: Ricerche storiche dedicate a Luigi Balsamo,
Biblioteca di bibliografia italiana, 148 (Florence: Leo S. Olschki,
1997), pp.1-23.