I cut the piece once more at 90 degrees and recombined the strips. I put a sheet of Bondaweb on the back and adhered a piece of heavyweight Vylene to the back.
I cut some 3 and 1/4 inch strips. Then cut 2 and 1/2 inch pieces. These I neatened off the edges with a satin stitch on the machine. I still have quite a lot of fabric left. I might make some postcard sized ones. Viola 4 ATCs - Artist Trading Cards.