matte is a finish, not a plastic lol the standard finish that will come out on it after being machined will depend on the plastic. after that it can potentially be re-finished via chemical, abrasion, heat, etc depending on the desired finish and the plastic. but you may find the standard finish is perfectly fine. If i understand, what you want made up is basically a surrounding trim that wont be under any structural load or exposed to environmental or chemicals? if that's the case then pretty much anything will do as long as its black. The only thing i'm not sure on is based on your drawing, the thinnest edge looks to be 0mm thick? this will be quite weak/non-existant and you may be better off with a few mm thick there also do you have the model in another format, all these triangles are driving me nuts. If not its ok i will just remodel it in a few mins. -update- i found a localish guy that will give me a sheet (20mm x 180mm x 270mm) of acetyl for $45-50 otherwise, are you willing to try wood? i can probably use some scrap mdf and then you can paint it black?