Measure your theater to determine how big your backdrop needs to be, and make note of the measurements. Additionally, evaluate the current stage setup to determine how and where you will hang your backdrops. Many theaters use existing rope-and-pulley mechanisms to hang canvas backdrops.
Purchase canvas according to your measurements. Remember to add a few extra inches to your measurements for seams.
Use a sewing machine to sew a casing along the top of each background for ropes or bars to fit through so you can hang the canvas behind the performance area of the stage. In addition, sew a 3/4-inch hem around the three remaining edges of the backdrop.
Sketch a rough outline of the scene you want on the backdrop. Mark which colors should go in which areas, similar to a paint-by-number.
Paint the background in layers, beginning with lighter colors and moving forward so the darkest colors are in the foreground. You may wish to hang the canvas once or twice during the painting process to visualize the finished process and make any needed adjustments, such as sharpening or blurring edges or adding or removing elements.
Allow the paint to dry completely, and apply a sealant over the finished product using a paintbrush. Once the sealant has dried, you can hang your canvas background for use during your production.