It is sheets of acrylic. It is cast and not extruded. Cast is best for the purpose I intend, but this makes the cost slightly higher at the same time.
The acrylic is 1" thick, and it can be cut to about any size. The pieces I'm interested in, are 12"x12". The pricing would depend on the size, but these particular pieces cost $18.50ea. with a quantity purchase. The cost could go down with larger quantities, but it would take a large order to make much difference.
I would recommend flat rate shipping, because the material is very heavy. I can cut these pieces down to smaller sizes if a 12"x12" is too large. I can also get larger pieces, but I have no need for them at this time, and the shipping would have to be freight I was told.
They have thicknesses up to 4" thick. I'm waiting to find out if they have any colors.