Determine the type of backdrop material you'll need. Small models or up-close shots may require something with more detail.
Pick a material for your backdrop. Stage productions and films may use fabric or wood backdrops while photo shoots and train models could get by with something less detailed.
Shape your backdrop material to fit in the background of the shot or production. Tight camera angles, which produce a close-up view, allow for smaller backdrops. Stage productions require much bigger ones. Cut your wooden backdrop, using a power saw, into the appropriate size for the job. Use scissors for fabric.
Paint your backdrop scene. Adding some mountains, trees and sky would be the simplest approach and useful for small models or possibly a photo shoot. The backdrop must fir the scene, though. A scene set during the winter should reflect the season. Other approaches, such as buildings or traffic, also work well.
Create a stand, through building a frame or attaching to cables or staging, for your backdrop to keep it upright. Prop it up near the back of the stage or behind where any acting or model set up will be. Hang your backdrop if you're working with curtains.