Just trying to determine 100% if it's acrylic or polycarbonate. I was fairly certain it was acrylic, now I'm 50/50. It could very well end up being polycarbonate, which would make it unsuitable for building a tank. I need to buy a caliper and measure variances. Polycarbonate is extruded and therefore has very small variances (.005")while cast acrylic would have quite a bit greater.
The upside is that 3/4" thick polycarbonate sells in upwards of $90 a sq/ft (so I hear) new and I bought these for $5.20 a sq/ft.