This is really fun awesome industrial racking. It makes two sided shelving that stick out 20" on both sides. It fits on 4"  pipe. It would be great for someone that likes old oddities. The listing is for 24 @ 20" arms. The pipe and bolts are not included. 

I have a large quantity available.
Pieces are very dirt, but for $500 they can be table blasted right down to bare metal. 
They could be used single sided, but would require a little work.