I know, I know... black iron gas pipes have infiltrated all things 'industrial', but there's a very good reason. This material is easily accessible, easy to use, has a great aesthetic, and best of all you don't have to be an arc welder to throw together a quick table frame for your projects.. I've seen a lot of really over done wardrobe units with superfluous arms for various uses, but personally I always like to air on the side of simplicity. Below are some of the ways I personally like to use gas pipe.
The only downside to this material is cost, it's not the cheapest thing to use, even a small project like the larger dolly above has a high material cost. Extra piping and embellishments can drive up this cost and translate as steam punk; which for me is just another reason to keep the design simple.