I was on Oh, Fransson today for something else and clicked her Small Projects link. I might try these colour block placemats sometime. Since her link is only to the 1st post in a multi-post tutorial on another site (and there are no links to the later ones from the first ones) I’m going to link all 4 parts here so I can find them more easily.
Part 1: fabric selection and cutting
Part 2: making the napkins
Part 3: piecing the placemats
Part 4: finishing the placemats