How to Make it..........
Either unpick your pre-made cushion including the zip, or get two squares of fabric 45cm by 45cm that work with your designer fabric
Get 2 squares of 45cm by 45cm designer fabric
With right sides together sew the front piece to the back piece, this will be the side of the cushion where the zip will go, so position the front pattern accordingly.
Using a zipper foot, pin a 35cm dress zip and sew the zip onto the seam you have just sewn, making sure it is exactly centred. You will need a zipper foot to do this
Open up the seam where the zip runs to expose the zip.
Open the zip, pin right sides together across remaining 3 sides, sew seam opposite zip first, then sew the remaining 2 sides.
Turn inside out to show right sides of fabric.
Insert cushion pad and you're done!!