Take 4 canvases of each size), paint them a solid base color and add vinyl or stenciled design. stick decals onto canvases, paint the whole thing and then remove the stickers to reveal the wonderful artwork!
An idea for some meaningful fabrics and old wallpaper, grandpa's sweater, grandmas dress. All in tiny frames perhaps with framed photos of family mixed in - need to do this! 39 Easy DIY Ways To Create Art For Your Walls
Beautiful cut-out canvas. You could leave them see through to see the color of the wall behind or it'd be easy enough to put craft paper behind which would be easy enough to change with the seasons or new decor.