This was my prototype.
Then I had some fun.
Start with strips of fabric that are about 4½" x 11½". They're placemats. The size isn't critical. Sew the strips together with a quarter inch seam.
Cut backing fabric to be slightly larger than the front. That'll make it maybe 18 x 12 or so.
Cut binding and bias strips. The bias strips should be approximately 1¼" wide. You'll need a strip about 40" wide (the length of your fabric) for one placemat. I cut my binding at 2½" Each placemat used about a 60" long strip.
Piece your binding strips together and iron them in half. Create bias tape by ironing your edges under.
Fast bias - just pull it under your iron.
Lay your backing fabric pretty side down and smooth out.
Layer fill and your topside down, smoothing everything out.
Pin your bias down. Do straight lines, curvy, whatever, but try to keep the bias over your seam lines.
Choose a stitch and sew down your bias. The beauty of this project is - you just quilted it too!
Square up the mat.
If you plan to hand bind the mats, go ahead and attach your binding on the front as usual. Because I'm going to machine stitch mine down, I'm going to attach it from the back so the pretty stitching is perfect on the front.
Voila. I did my placemats individually when I had minutes and found they took about 35 minutes each. If you had the time to do each step once for the entire quantity of mats you need, I bet the time per each would be cut down substantially.