I bought three different types of dense paper/card stock and wrote the prices on each. And comparing them to each other and to standard mat board.
In the Illustration Artboards there are ten sheets in the pack that are 8"x10" for twenty bucks. So it's 800 in^2 for 2.5cents per square inch. The marker boards and lettering boards are three sheets per pack of 11"x14" for thirteen bucks. That's 462 in^2 at 2.8 cents per square inch. For comparison, Apogee sells centering ring card stock for $2.72 for an 8.5"x11" sheet. That's 2.9 cents per square inch. The shipping will add at least another ten bucks or more to your order though. All the material I bought is also available on Amazon so if you're a prime member there's no shipping of course. And you'll get the stuff faster if you need it.
I started with Illustration Artboards. If you're doing the math, the 800 in^2 is 2,032 cm^2. So if you're cutting rings for, say, a bunch of bt-50 tubes, they're roughly 4.52cm^2 in area with a 24mm diameter, so you are using 5.76cm^2 worth of material (I'm accounting for waste around the ring by using squares rather than circles for the area) so you get somewhere around 300-350 rings out of the ten boards. Or if you cut rings with as much waste as I do maybe 150. So your rings are costing you 13 cents each to get 150 of them. Or half that if you're a true craftsman unlike me. Apogee charges 54 cents apiece for bt-50 centering rings. Plus shipping of course.
It is denser than mat board. These are the weights of the same size piece:
I didn't bother to calculate the weight per inch or cm but based upon the feel the illustration board is likely close to what centering rings are cut out of by Estes/etc.
I bent them to see about delamination (which mat board does very easily). The illustration board is far more resistant to it than the mat board:
I rough cut rings intentionally being sloppy to damage the edges as much as possible. As you would expect the illustration board is tougher to cut but again is far more resilient than the mat board.
Bending the larger sheets did cause sharper cracks in the illustration board than the mat board but that's kind of what I expected when I brutalized them. The illustration board does have branding on one side but I don't care about that. Maybe you do.
I will do the other boards when I get a chance, as well as gluing. Thus far, however, the illustration board seems like it's good stuff.
More to come.