This simple pattern for a corner-to-corner square cushion cover is a great way to learn Tunisian simple stitch, double crochet, slip stitch, and colourwork. The bias construction means that you can easily adapt the pattern to any cushion size - just keep increasing until the project reaches the diagonal width you need for your cushion. You can sew this onto an existing cover, or make 2 additional panels for the backing. Any worsted weight yarn will work here, as gauge is not important. A self-striping yarn would be especially beautiful but I use Cascade 220 to demonstrate. 2 colours are needed to create the beautiful effect of brick stitch and wave stitch. All techniques are demonstrated in a video on the Loveapple Crafts Youtube channel:
https://youtu.be/T0UTOFKvWTs