There are commercial shelf rests available, made to fit certain brands of bows, like Black Widow. However, shelf rests and strike plates are very easy to cut out of leather, Velcro, or rug rest material. They either have a peel off backing, or you glue them on with some kind of removable cement, like Barge, so you can easily change them later. The type of material affects where the arrow hits: if your arrow usually hits left (for a rh shooter) you can move the POI to the right by going to a softer strike material. Make sure you take care of any form issues that might be causing this first, however!