acrlyic

[NYPDFrogman]

Besides asking the manufacturer, is there an easy way to tell by looking at it, touching or .....

Thanks in advance

yes you can see faint lines ( extruded it's forced through a mold)
it's ususally marked on the masking.
cast will chip or shave when being worked.

heat from the friction of the tool will cause extruded to gum up.

extruded also feels more flexible than cast.
the stuff in HD is import extruded and should not be used.
you want acyrlite GP, plexiglass GP, or lucite GP
use weldon 4 (pin method) to bond the material

I'm no expert on acyrlic but I've built my share of tanks, sumps and reactors