Finalize the size of your stage background based on how it should cover the background space in your actual stage location.
Sketch how your stage background would look, then make a layout on how it should be mounted to the stage. This also allows you to determine the specific materials you need for your stage background construction. Often times, a fabric with a frame made of PVC pipes are used for a homemade stage background. In some cases, Styrofoam, wood, plastic or metallic sheets are used instead of fabric. Using a fabric is common because it allows more convenient painting of a background whether a landscape, an interior or exterior of a house, a castle or a fantasy land.
Buy your construction and painting materials based on the needs required by your sketch and your layout. Also, prepare your basic construction and painting tools like hammer, screwdriver, driller, adhesives, paints and paint brushes. Use matte paint to avoid unnecessary reflections on your painted background caused by stage lights falling onto it.
Cut your fabric canvas according to the measurement of your intended stage background. Place it on your work area, which is ideally covered by newspaper pages to avoid leaving paint on unlikely spaces like your floor or your work table.
Make guide sketches around your canvas using a pencil, then prepare your painting materials and tools.
Start painting your stage background. Once done, allow it to dry for a number of hours. Usually, it is better to leave it overnight.
Spray the painted background with a matte finish sealer spray to protect it from chipping and cracking.
Attach PVC pipes or pieces of wood on the left and right sides of your painted canvas to serve as your stage background's mounting frame. Some prefer attaching the canvas over a large wooden board, while some prefer surrounding the top, bottom and sides of the background to create a more secured frame. If you are making a small stage background, you may be able to use a curtain rod or other similar materials for your frame. There are some who simply hang the painted canvas from a stage rig or the ceiling. There are also those who tie the background's ends on specific parts of the stage.
Mount the stage background on your stage, then make any necessary adjustment based on how the stage lighting affects you painted background and how safely and securely attached your background is on stage.