I love laundry sinks! If you had the counter made, not bought at a big box store, ask if they have any scrap pieces in the same or similar material and attached rubber feet to put it so it sits flat on tile of the sink. You could also get the right size butcher block chopping board and do the same with rubber feet to prevent it from sliding or shifting when out. A metal baking pan might come in the right size. Good luck!

I meant top not tile of the sink. Wish you could edit on IPad.

You cover that sink and it'll never get used, I promise.

You could put a shorter door on upper cabinet and the now open lower area would be a flat shelf.

Just keep a folded up TV tray in there and open it up when you need it or put a fold-down on the wall.

I use our laundry sink all the time, and it is approx the same size as the one in the OP's photo. I would not cover it.

A large cutting board will cover the bowl of the sink and should enable you to use it w/o changing the sink/vanity itself.

Alternately, if you need to cover the faucet, too, create a wood box as deep as the faucet (plus a half inch) that is the same width and depth as the countertop and set it upside down atop the sink.

Can you even spread your elbows out in that tight spot?

So ......"by design" wasn't great design? Skip it. Cover it why? to fold? You won't use it. Fold as you remove from the dryer. Put in basket. Easy Peasy.

Great use of space. The sink will will come in handy. I have one in our laundry room. Do I use all the time, no, but i’m glad I have it.

https://www.menards.com/main/plumbing/utility-sinks-accessories/mustee-reg-utilatop-20w-x-20d-white-laundry-utility-sink-cover/19-204a/p-1444429941785.htm

Use one of the roll out dish drying racks.