Then with a cross-pean hammer put a taper to the ends.

Mount it on a vise between steel plates.

Hammer it to get to a 90 degree angle.

I already forgot the most important part of all: ANNEALING. Copper is made softer by annealing and hard by hammering or working with it. So as often as you deem it necessary heat it up to red and quench in water to anneal it.

Clean up the inside surfaces with a file or grinder since after the second fold it will be much harder to get in there.

Then take it to the vise again and position it between steel plates so that you can hammer the second fold.

Like so.

Now you have to refine that curve into a square.

I will use a hammer a a scrap piece of steel of the approximate width of the sword's nakago to do so.

Then I need to make that bottom inside curve into a square too. I will take my scrap piece of steel and hammer it in.

Like so.

Then it goes for a test fit on the blade. Note where I have marked the dimensions of the mune machi so that I can either hacksaw or file that notch in the habaki.  

Like so.

Test for fit.

Then cut off the excess copper at the bottom.

Like so.

Here is a look at what we've got so far.

Now comes the easiest part by far, it is called the MACHIGANE. Whoever invented this little contraption to make it all fit together should have been invited to test the sharpness of the edge of the sword for which that habaki was made. It will take me sometimes an hour or more of fooling around with this little copper piece to get the right fit.

Then it is time to hard solder all together.

Like so.

Let it cool down by itself in the air.

And now we have a rough shaped habaki.

Start working on it with files or a grinder and get it closer to your final desired shape.

I will use machinist marking ink and a pointer to trace the final contour.

Then it is more grinding, filing, sanding or buffing to get to the final product.

And here it is fitted to its sword.

 I use hard silver solder for making these fittings. The strength of the bond created by the hard silver solder seems necessary for pieces like these. Once the habaki or the fuchi or kashira is constructed using the techniques described above or variations of those techniques you can then texture it or carve it or patinate it.