I think you'd do better modding something up out of pipe. Pvc is inexpensive, andeasy to work with, and if you heat it you can shape it. (be careful!) Copper would be easier to bend for the curved bits. Could probably mold it around a 5 gallon barrel to get the curves. However I would worry about it deforming/bending under pressure.
Then once you have the wheel shape you want, graft it onto an existing yoke, aka franken yoke it.
![Smiley :)](http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
To get really realistic looking is going to take some serious time, planning, and attention to detail.