Now, I do work at Target, so I decided to see what we had... then I found it - a nice 15x24-ish pet food dish mat. Raised edges to catch stuff, easily cleaned with damp cloth and black so most parts stand out while building. I got it yesterday and started right in - it was perfect… and costs under $7.00 before shipping. Most Targets have it in-stock, but alas mine did not, so I ordered it on-line - just thought I'd share.
https://www.target.com/p/feeding-mat-for-cats---38--dogs---l---black---boots---38--barkley--8482-/-/A-53455565