My husband built an extended window sill "shelf" for windows that we use as a pass-through in the summertime. He went to a specialty lumber company where they have extra wide boards. I know ours is solid maple.

Or you could contact someone who builds dining tables, and they could custom something for you.

You could contact a MILLWORK shop in your area. They would measure and fabricate whatever design, wood specie and finish you select.

Hey, thank @Mary Elizabeth and @BeverlyFLADeziner, I will try to check local millwork shop. Thanks a lot.

Called store and the size is an issue (10 ft by 14 inch), they usually have 12 inch width one. Anyone knows what kind millwork store carries special size

Again, I think someone who makes custom dining tables could help you. Not sure if you're looking for wood that will be stained or painted. But they could seam two or three boards together using "bisquits", and also route the edge if you need.

It should be easy to find someone through google or even FB Marketplace.

If it were me, I would want the person doing the work to also be the one to source the lumber.

" Anyone knows what kind millwork store carries special size "

You will not find it in a "store". You either need a custom millwork shop or possible a real lumberyard that supplies boat lumber possibly or has a shop. The best way is to have two or more boards edge joined.

Thank all of you for your suggestion! OK, now I see the most possible solution is still to put 2 boards together. Will work with my installers about it. Thank all of you!