Edges can be bent completely by hand, but a few simple tools help save your fingers. For snowboards I just use the modified ring roller below to get started and do the rest by hand, but for skis I find that the hand tool is required to get such tight bends done well.
Modified Ring Roller
I use a modified ring roller from Harbor Freight (part #36790) to put an initial bend in edges and then finish them up by hand. The center roller was modified on a lathe to make a slight notch for the bulk of the edge, and an extra disc is added on the outside to support the tines. The disc is held away from the main cylinder by a few thin washers.
Getting the edge started in the roller is hard when the rollers are adjusted for a tight bend. I place a marker on the adjustment knob so I can turn it back some number of turns to get the edge just started, and then reset it to the tighter radius to start bending.
There are a bunch of guys on Skibuilders.com who have built benders like this but with the rollers oriented vertically instead of horizontally. This allows the edge to stay flat on a table while you’re bending it, whereas with mine I have to hold the edge up quite far as I roll it back out of the bender. The vertical roller way looks much better, and one day I’ll get off my butt and build one.
When a really tight bend is required the leverage provided by some modified nippers is perfect. With a little practice you’ll be able to add a smooth bend exactly where you need it, or undo an accidental kink with ease. These are very easy to make with a bench grinder and/or a Dremel tool. The “nippers” are called different things; you might see “concreter’s nippers”, “wire nippers”, etc. The pair I modified were from Lowes and cost less than $20. It took about 15min to modify the nippers.
Grind one side to leave a narrow “finger” in the center, and grind a notch in the other side for the finger to fit into with plenty of room to spare. The original edge of the nippers is sharp and hardened, which is good because it will help grip the steel edge without slipping, so leave the original edge as much as possible. Practice on some spare pieces of edge and you’ll quickly learn to make very fine adjustments very accurately.