Krypton by joycall3

Notes:

dA source

I know krypton is not in portal gun or weighted companion cube, so I checked in the other site where the artist uploads his/her pictures.

Apparently, krypton is used mostly in fluorescent lights, infrared laser, neon lights, magnetic resonance imaging, etc. So, the artist simplified this concept to "laser". Since he/she liked the idea of using portal gun somehow, the artist picked portal gun as a reference.