Oil pastel on black paper, if I remember right. (I have the original artwork stored somewhere in my house, but I'm only looking at the digital versions as I write this.)

This artwork was inspired by a dream. In the dream, there was an infinite grid of glass furnaces in space. To get between the furnaces, there were walkways (to go side-to-side) and ladders (to go up and down). This artwork doesn't quite do justice to it, because I only focused on one furnace. I didn't find a nice way to fit the others in the background. I probably should have done a sketch first, so that I could express the absurdly large scale of the space.

To get a sense of the scale, the tiny white ladders I drew on the sides of the furnace are intended to be sized for a human to climb.