Thank you, ACM is aluminum composite material. It has a solid plastic core sandwiched between two sheets of aluminum. The aluminum has a baked on polyester paint finish. It is very stable, used for signs and skinning buildings. I abated the surface a bit making sure not to go through the paint. Then I apply a primer-sealer (Zinsser 1-2-3). It bonds well and give me some tooth for the paint. You can use it for oil painting also. FB painting best practices talks about this stuff and also mentions a version that has canvas mounted to it. Art supply houses are selling it primed for painting. I just buy full 4′ by 8′ sheets and cut it to size. It cuts with wood working tools just fine. You can bend it and it will hold that shape. Dibond is a brand name of the first company to produce this stuff but there are others that are less expensive. Look up all the things you can do with this stuff.