I have an aluminum jack stand. I also use wood when it is very wet/muddy.
I've tried plastic blocks under the jack, but stopped. It deforms under load when the ground is soft and deteriorate when exposed to UV. Some even have an expiration date printed on them.
dgk is a forum member, Deb Kyle is her name. Her dad started an aluminum casting business making cone style jack foot stands, wheel chocks, and sewer hose supports. After her dad passed she continued his business.
There is contact info (and photos) here>
This is what I use, purchased from Deb>