Thanks again for replies 
Kudos @Paul_KD7HB, I had to google "spring loaded split gear" and it's something I have to look into, thanks!
MarkT:
A servomotor is what you are looking for. Only uses the power needed at any point in time.
I don't trust gears (at least not the gears that fits my budget) 
MorganS:
(...)
Any gearbox using a worm gear is considered "irreversible" meaning that the output cannot be moved unless the motor is powered. If the steppers don't work out, look for gearboxes with worm gears.
Theoretically, yes. But still gears :
I'll finish my project using steppers, because I want to try my theory 
https://www.youtube.com/watch?v=Y2WZQaG6Kp8 - this thing uses steppers. I can see a lot improvements there while still using steppers.