I finally finished the seat.
I figured out why I was having so much trouble with it.
I initially used a 3-inch thick piece of foam but could not get the corners smooth. I know this is just a shop stool but this really bothered me (I can be somewhat OCD sometimes).
I went back to YouTube and after watching videos again found my mistake, the foam was to thick.
I pulled off all the staples (there was a lot of them) and removed the cover. Using a bread knife, I sliced 1.5-inches off the thickness. Using the corner technique in the following video, I tried again and this time got the corners perfectly smoothed.
Some advice based on my experience.
If you try this, be careful with the heat gun. Use a low setting or do not hold it to close to the material, the vinyl gets very hot very fast.
A manual staple gun will not penetrate plywood. I initially tried using my Arrow T50 PowerShot. The staples barely went in and hammering them caused them to bend.
I realized I needed to try something else. I thought of using nails or tacks but decided it would be more difficult in trying to hold the material taut and drive the nails at the same time.
I bit the bullet and bought an inexpensive pneumatic staple gun which made a world of difference.
Overall I am rather pleased with the result.
By the way, the fact that it is color coordinated with the bench is no coincidence. :biggrin2: