[NH_Bulldog]

It is the same/similar to batten strips used in mobile homes. If you have a mobile home dealer nearby, you might be able to pick up a few there. When I was in the business we had literally hundreds of “spares” in stock for our service side of the business for both patterned wall panels and plain ceilings. Manufacturers changed their decor yearly so we always had a lot obsolete colors and patterns that we gave away to anyone who asked.