Original Piece of Foam With Cuts
I started with a piece of faom 19" x 8" x 3". I knew I wanted the cushion to be 16" wide, so I started with this chunk. I used my bread knife to cut the foam. However, when I bought the original piece, they cut it with an electrical knife. That works much better; makes a smoother, cleaner cut. I do hope you can see how I slice this piece to make the two parts.
Cutting and Trimming the Pieces
After slicing the piece of foam, I cut off the little ends and took out the chunk I needed gone in order to make it good for my spine.
Checking How the Pattern Pieces Fit
I highly recommend this step. I found I had forgotten the seam allowance on one piece. Better now than after the fabric is cut.
Checking How the Sewn Fabric Cover Fits
This gives a little reassurance that things are going to fit.
The Finished Cushion
I sewed the two pieces together at the center of the top. For easy carry, it will fold on this 'joint'. I'm sure you will do a better job of sewing. However, the 'sitting test' gave my new 'watermelon cushion' high marks. Very comfy. I'm all set for that long long long trip to Houston.
What would I do differently: allow more time, make my pattern a little more accurate, and try to work when I am not tired. My pattern was a bit sloppy and the fit is very loose. I could have cut those pieces a little smaller. Just very happy it is DONE. Done is alway good!