First using the pen tool I quickly blotched out the position of the creature. And the rock he is on.

Next I stretched out the snout of the gas mask a bit, as well as extended the top of the head up a little. Then using the cheek of the mask, I guess you could call it, I made the pieces of the body. Just transformed and warped the chunks a bit to make them fit the way i wanted.

Next I started in on some shading. I decided my light source was going to be from the top right so I painted in shadows accordingly. Using a few different brushes, the chalky texture brushes that are in the regular photoshop brush pallet.

More rough painting over top of everything.

Still just more painting. I kept making a new layer and painting for a while then turning it off and on a few times to see if I liked where it had gone. Often I would scrap the layer and start again. Or just lower the opacity of the new paint layer then merge it down and then start on a fresh layer.

Ok now I created the tube. First thing I did was just make a line with the pen tool. Then set up my brush to a hard one at the width I wanted. then I stroked the path (without simulating pressure).

I applied a layer style of a slight bevel emboss to it. Then I took the piece from the mask that is the edge of the other eye hole that you can see a bit, and used it to make the little pieces on either end of the tube.

Then, using the same path as before I reset my brush to a higher opacity and a smaller softer brush. Then stroked it again on a new layer this time using pen pressure. I did this a few times and move them around to get reflections that I liked.

Then I stroked the path with a bigger softer brush once more and added that to the bottom of the tube.

I then took the piece I had created and copied it and warped it and all that fun stuff and put it in various places. I moved them around a lot till I found something I liked.

Next I took the circle piece from the mask, which by the way at some point earlier I added a few more to the face....anyway I warped that piece a few different ways and painted it a little darker then put it on the arm and a few more on the head. Just to add some detail. Next on a next layer with the layer style bevel emboss turned on, I painted some lines with a small hard brush to make it look like he was made up of many metal pieces. then with that same small circular brush on the same layer I added a bunch of screws.

Then I used some render clouds to add a smoky effect. I masked out most of it, and set the color overlay in the layer style to a dull green color. I also painted a bit in the top right corner with a huge soft white brush to add to the haziness.

After adding some smoke coming out of the "mouth" I just did a bunch of minor tweaking. I smart sharpened it a bit and up the contrast a little that sort of thing and then it was done :D