An anon wanted this box thing for doing perspectives in a more tangible manner. Dunno which one of you stinkers it was so I'm just throwing it out there without replying to the previous comment.
It is a .csp file (for Clip Studio Paint). It'll load up as a object and you could (presumably) download these directly into your material log. I guess the other guy has a cracked version? Hm.
>aHR0cHM6Ly9maWxlcy5jYXRib3gubW9lL3hmYjkzYS5jbGlw