I made these simple shape sorting mats after I could not find what I wanted online. I make 4 copies to use as a center activity and I color code the pieces for easily cleanup. I hope you find this useful!
Tip: Print the mats on 11x17 (A3) paper and laminate. Print the shapes on different colored paper to easily sort when/if they get mixed up. Use velcro to secure the pieces to the mats.