Make Rough Walls in Photoshop

[JFJohnny5]

Does anyone have any ideas on how I could make "rough walls" for cave maps using Photoshop? And just to be clear, I'm talking about the actual outline of the wall itself, not the fill or any kind of texture issues.

In the example I've attached, I'm trying to get something similar to the top half. I can use a grid and the pen tool to reproduce the straight walls form the bottom half of the map with little to no problems. But I can't figure out how to use the same pen tool and grid application, but then come out with the rougher cave walls. I could of course use the pen tool to individually make every bump and recess, but yikes! I can't help but think there has to be a way to make a straight line and then add "the noise" so to speak. I guess I'm looking for something similar to the fractal line tool from CC3.

Once I can get the wall outline, I'll be creating various masks and using effects such as stroke and bevel to get the final look. I'm just stumped on step 1, making the wall outline itself.