Thank goodness we don't have to put zips into cushion covers any more, making one is now a lot easier than it was. I started this one a couple of weeks ago, I picked two contrasting cotton fabrics and cut 36 squares, 18 of each. This size will easily accommodate the cushions I already have, no need to buy any new ones. I hand stitched them together in the same way I did the quilt.
Here is a video explaining how to make the envelope cushion. I ignored her measurements, I placed the patchwork on the fabric and used a long ruler to mark out the size with a pencil. The overlap doesn't have to be exact, as long as the back doesn't gape open. I needed to make mine in this way because of the way I incorporated the patchwork into it.
Here is another video with an even easier method to make the same thing, if you are not adding an extra layer of patchwork. This is very simple.
I have got five more cushions in need of a makeover, the next cover is already started. My cheerless living room should look a whole lot brighter with these extra additions. I might even remove the dustcovers from the three piece suite, mind you that will upset the cats as they like to play hide and seek underneath them.