Purchase pieces of foam board at a craft store or Lowe’s. (I think it cost about $10 for a paneling-size piece.) Then cut it in half or thirds. Cover it with fabric, decorate it and hang it in your wall.
I covered the foam board I bought in burlap and used wallpaper sample guides that had been sent to me by a company. The result was a colorful, modern art display.
You can also cover the foam boards in fabric, wallpaper or anything you think would look like a nice art piece. Depending on what fabric you use, you can draw, paint on the canvas or add photographs.