Like this... but possibly with swappable dies and not expensive? I have a big bender for roll tubing but the dies for just one size are $225 or more (depending on radius).
Tubing would be ... .047 wall probably? Good strength for making things like ski racks, kart bumpers and so on but as light as possible for the job.
I use a conduit bender for small, thin tube:
You need one for each tube diameter, but they are cheap...I think I paid $30 for a brand new cast iron one on Craigslist. You want an iron one for this kind of abuse. 
In reply to bgkast:
I like the one in the pic above because it has the roller to keep the tube seated and let it stretch. The tube I'm planning to use isn't soft - it's steel DOM tubing. It also appears that .065 is the thinnest wall I can buy locally. That might be pushing it for a conduit bender. I may also need a tighter radius (IIRC those are 6"?)
I did find a couple nice ones from Baileigh in the $200 range but they are single size... making it about equal to me just buying dies for my jumbo bender.
I wish I had thought of that when I bent my 3/4 inch, I used a coiled spring to hold the form and hand bent mine over my knee. That was AL though so I'm not sure I could have done it with steel. Looks like I will be buying a conduit bender. Thanks Bgkast.
I'll be watching this. I am looking for something similar for fabricating a motorcycle subframe.
JD squared, die sets will always cost some coin, but will last, cheap die sets scare me
I was bending 0.065 wall 3/4" DOM with mine. It wasn't easy (hence my abuse comment), but it worked.
You could heat up the pipe a little before bending it with the conduit bender. I've bent steel gas pipe with them before. You could also use one of those bottle jack benders, but the dies for those are sized for pipe, so 1/2" would actually be for 1/2" ID pipe with an outer diameter of 5/8".
I have one like this for 3/8 inch tube, and it rocks. 180 bends in 3/8 fuel line with no crimping at all. If I had known how well they work, I'd have spent the money 30 years ago.
However, I bet its not what you are looking for, and the biggest is 1/2".
http://www.swagelok.com/search/find_products_home.aspx?show_results=Y&item=4f9d4893-970a-4488-a9c9-501f774bb60d
captdownshift wrote: JD squared, die sets will always cost some coin, but will last, cheap die sets scare me
I think this is where I'm ending up - I called them and they will make a slight deal on two sets so I can get both 3/4 and 1" 180 deg for the bender I have already in a 3" rad. and they do up to .134 wall so no issues with tubing choice. If I had to pay someone for what I want to make it would cost more than the dies so... (sigh) guess I'm spending more than I wanted but less than I could have to. Now I need to find more things that need making in those sizes to sell and recoup!
I did the special coil spring deals that go over the OD for some stuff. It was OK, but only just. It was a lot of work on the 3/4" stuff.
Used these Ridgid geared ratchet tubing benders at my old work place for bending steel hydraulic tubing. IIRC, available in 1/2" thru 1" in 1/8" increments, 180° max. Not feasible for what you're doing as rather pricey for just one size, more than the JD die set... but they will spoil you.
But if I ever stumble across a used bender for the right money, I'm in.
This design should be adaptable to what you need.
http://www.youtube.com/watch?v=lcTIDlDevog
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