My projects were lightswitch and power outlet covers.
I found and purchased the blank covers. Then I spray painted them a flat color. Then I put vinyl cutouts of different shapes onto them and spray painted them again, peeled off the vinyl and then used ink, acrylic and collaged stickers that I had into the completed covers. For future refererence though vinyl pulls up spray tape pretty easily so if you don't want the appearance to be rough and uneven when you tear off that layer, maybe some other material might be better to use.