Our trailer didn't come with sink covers, and I found the price for the factory ones prohibitively expensive, so I went about and made a set out of some 3/4" pine shelving I had lying around. They were okay, but I still wasn't happy with them:
So I thought I'd stain them to match the rest of cabinetry. The stain color was close enough, but IMHO they looked even worse:
I shopped around and bought the biggest polyethylene cutting board I could find. This one is 18" x 24" x 1/2" of food-grade poly:
I made a template, threw it out and made another one... over and over until I got one that I was happy with. This is the key; that little jog at the top of the larger sink is a pain to deal with, and only with a proper template can you get it to fit. Polyethylene can be worked with woodworking tools, and fortunately I have a decent table saw and sander to get the edges straight and smooth.
A couple of 1" holes make it easy to remove the two parts of the cover.
Cross another one off the list.