I found this cool creamy white wool vintage coat at one of my thrift shops. The first thing I always do with wool is wash it in HOT water and dry it in a HOT dryer. This assures me that I will never be visiting the dry cleaners. (I have always known that wool is SMART!)
After wearing it 3 times I decided it was ready for it to cross-over.
I cut and frayed the edges of random squareish shapes. Using waterproof white glue I glued the shapes onto a nice large piece of brown tarp canvas. I adjusted the size to exactly what I needed for a cozy fit right up to the curvey vintage green tub. Letting the brown canvas peek through around the wool shapes gives it a mosaic look. Feel free to overlap if you like that look better. You can actually pile on the wool/terry cloth/tapestry/etc etc to make it thick and absorbent.