http://stunthanger.com/smf/open-forum/a-day-in-john's-shop-horn-bending-jig/

Go to this link in open section.   Also of you do a search on SSW for Derrick Berry's  wire bender and solder tool.

I made this simple horn bending jig from piece of 1" steel square stock and some 3/16 x 3/4 steel dowel pins [McMasterCarr].  Used the other end of handle that came with the K&S 1/8 bender which I already had, but you could also sub a piece of 3/8 x 1/2 flat bar for handle stock.  This jig gives you exact distance between arms and makes sure they are bent paralled to each other.   You could set up the opposite side for a different wire size and / or arm spacing..  Drill press and Accurate layout required..

I've been using the unit pictured (I  hope) below for bending landing gear wire.  Very repeatable results are possible.  I clamp it in a Work Mate or bench vise as needed.  Cost back in t he day was about $50 to $60.00 I think.  Very much over kill perhaps but.....  You can set it up to perform repeatable length bends and such which is nice.  or even bend two pieces of wire at once.  It's generally call a "Universal Bender" in most catalogs.  Mine came from Busy Bee Tool in London Ont.  They show a more expensive unit in their catalog now.