Steampunk Portal

I was sitting around at Swancon, chatting with friends, and the idea of Steampunk Portal came up. ...and we got thinking, how on earth would you make portals in the early industrial era? Oh crap, you'd have to *dig* them, wouldn't you? With your steam-powered pick.

And well, Portal, being made by Valve, available on Steam? It just kind of needed to be done.

By the way, I've finished Portal 2, but please refrain from spoilers in the comments as others may not yet have done so.

Also in my Steampunk Portal themed series:
The Gentlemanly Escort Cube
The Wheatley Dumbwaiter Service

Time: About 7 hours
Tools: Photoshop CS4, Wacom Intuos tablet, cgtextures