Layered / inlaid acrylic piece. The black 311 is inlaid into the white border. Both are then placed on a layer of red then black. CA glue to hold it all together. Finished size is 10x18in (I forgot my banana ruler )
Colored acrylic is from Delvies: https://www.delviesplastics.com/c/laserable-plastic-sheet.html