This is what I use because it was a leftover at the farm before I moved to the lake. When I move again later this year, I will buy a slightly longer piece of particle board and paint it before I put it at my sewing table. It works just fine for me!
From Lowes:
https://www.lowes.com/pd/7-16-CAT-PS...4-x-8/50382768
(cheaper than HD)
From Home Depot:
http://www.homedepot.com/p/7-16-in-x...6081/202106230
Jan in VA