custom sump pump basin cover needed

When I bought my house it didnt have a sump pump basin cover. I've tried to purchase one and none of them seem to fit my fiberglass basin size. The inside dia. is 19 3/4". My initial thought was to custom make one out of plywood by cutting it into a circle and then cutting it in half thru the two pvc pipe exits. Any ideas/advice on how to do this is appreciated. Are there any companies that custom make covers or that have my size?
Thanks for your time.

I would make a notch that would let the two pipes come out, but leave the basic cover in one piece. Then, put two small pieces across the cutout piece so it would be supported on the main cover.