Q&A for How to Make a Movie Set

If green screen technology is available, use that. If not, perhaps limit your shots to indoor scenes, and have your characters pretend they're in a city. Models can also be a solution, but they're a lot of hard work. Finally, if you really can't go to a city yourself, you could ask any city-dwelling friends you may have to make the shots for you and send you the files.

Yes, cardboard would make great walls as long as you can decorate them sufficiently!

You can ask your parents help, and any other adults that you think could help.

Consider using scale models, then using normal rooms and close-ups for the live action. In "Indiana Jones", for example, they had to ask an entire town to remove their satellite dishes. "An extremely low budget" does not allow for such ideas. You can go to a medieval town in France, for example, but unless you live in France, that will eat a chunk out of your budget, too.

It depends on the extent to which you do so. I'd suggest you formulate a strong idea of the set ahead of time. The more you plan, the smoother the process will go later on and the more you will be able to budget. An early plan will also create a more cohesive whole, meaning a better tone and overall visual product. However, when planning a set, one must must must remain flexible as unanticipated problems always present themselves; that is when the improvisation comes in. You'll do best if you plan ahead but think well on your feet.

Most indoor scenes are filmed in a studio, with the rooms built with only three walls so the camera is not blocked by a wall. In "Leon, the Professional", for example, the outside of his apartment was filmed in Paris, the inside in a studio in London. Usually, people decide what they want their scene to look like, then look for a place that fits their criteria. If you want to build sets for live action, you'll need a hangar or barn, someplace high enough to build a room in.