Bence-
There may be an alternate motive for making a bonsai, other than fun or aesthetics.
In one of the links I posted, it details how to start the bonsai and also how to take 4-6" cuttings in the spring. Some cuttings root in as little as a few days or up to 2 weeks. And a week after taking the first cutting, the bonsai is ready for more cuttings.
Doing the math, in 2-4 weeks, you can have quite a few 6" cuttings growing. Considering some varieties take 4 weeks to even germinate and up to 10 weeks to get 6" tall, this could give a person a big jump on the season.