Rapid prototyping (RP) is the theory of prototyping with many iterations in a relatively short amount of time. Generally, these prototypes can be executed rapidly at the cost of a lowered fidelity. This can be an effective way of working, since one can try out a lot of different ideas and angles, to find the best suited idea. And a bonus is that if the main idea should prove to not be viable, you would have a lot of already tested ideas that you can fall back on.
Common ways of creating prototypes rapidly and with many iterations is
3D printing
Laser cutting
Milling or turning (to a certain extent as these processes takes up more ressources)
Paper/cardboard
A 3D model being 3D printed
Of course, the production method and fidelity of your prototype should match your goal with a given prototype. If the prototype is for a user interface user test, it should probably not be made from cardboard, as that wouldn’t give the tester a proper impression or feel for the user interface. And if the prototype is strictly to determine feasibility, you probably shouldn’t start off by ordering a milled prototype as that would be too expensive and way overkill.
