Well, I needed a coaster an thought I'd have a go of making one.
It's made from fabric and plastic with pictures visible from the top.
I played around until I came up with this method (though I'm sure it probably exists out there somewhere already :p)
From the bottom up it goes:
fabric, plastic, fabric, pictures, plastic.
Stitched all the way around and trimmed.
No more watermarks for me!