Using a IKEA Mosslanda picture ledge, I added a couple of supports and transformed it into a window sill shelf to allow me to add more plants. Total cost was about $20 and didn’t require any drilling or nails. All you need is some strong wood glue good double sided tape or velcro. I’m a huge fan of the 3M command strips and would highly recommend that.
3M Command Picture & Frame Hanging Strips