Just create your own sink cover by using a cardboard template and make from wood. Measure, template, cut, sand, finish, DONE. Better yet, instead of finishing with stain and/or varnish, use a food safe cutting board oil to make it a productive cover that doubles as a cutting board.
DIY awning cover: Make an economical protective cover for a roll up awning WHEN TRAILER IS STORED at home. Use two section of black corrugated black drain field pipe without holes. Use a battery saw and cut a two inch section out the length of both pipes. They snap over the rolled up awning, blocking hail and sun light.