If you don’t want to go through Inventables for any reason it’s also stocked on Amazon
4 Pack, Laser-Plastic-Engraving-Sheets- Mattes White/Black 1/16 Blank Interior and Exterior Grade 2-Ply Plastic Engraving Blanks - Non Glare https://www.amazon.com/dp/B06Y1VQYCW/ref=cm_sw_r_cp_api_i_g7N.CbVAXZQ8Y