The Film production cape is made from a custom made, electrostatic flocked (on the outside only), ultra light weight ripstop nylon fabric with a 3mm square pattern on the inside surface, as shown in the following two photos.

It’s also worth noting that for the Nolan films, they created 50 capes in total, varying in length, shape and size to reflect different functions such as trailing, walking, action/fighting and mechanical. 
The long billowing cape that drags on the floor is not practical for a costume suit, as it would not last five minutes before the bottom was ragged and covered in mud, so I decided to make mine to sit just off the ground.  Imagine getting your cape wrapped around the rear wheel of your Batpod and ending up in Gotham Hospital!

I have built three capes now for my suit, the first two from a set of curtains with a really cool black fabric – Click here if you want to see how I made that version. For my third cape, I moved away from that fabric for two reasons: the fabric sticks to velcro and becomes fluffy and damaged really quickly and because I wanted to get the velvet look and feel of the genuine flocked fabric.

In the absence of the genuine flocked nylon fabric, I have bought some 6m of a lightweight velvet upholstery fabric, with no stretch (lots of velvet fabrics are very stretchy).

I also want to give a shout-out to my friend Jimmy Corneth from Scratch FX in the Netherlands, for sharing his knowledge and research on the screen used capes with me. Scratch FX now make capes from screen accurate nylon which they have had flocked, so if you don’t want to make your own and you want screen accuracy, check them out here: https://www.facebook.com/scratchfx/

I have gone through all the stills of the screen used capes I could find and I have made my own pattern, based on Jimmy’s design, my research, my own height (170cm) and design choices around fitting/mounting. I am calling this cape v1.0

Using thick paper, I made my templates, based around a central fold for ease of symmetry.

I then made a small scale version of the panels and the fabric, with 1m marks on it to work out the best placement to get them to all fit.

I then cut them out of the velvet fabric and pinned the panels together face to face, before running them through an overlocker along each join, then all around the edges of the cape to stop the fabric fraying.

This next photo shows my old cape, but I have used the same mounting design, attaching short straps to the two top ends that go over the shoulders, with a metal dome snap on each one, that attaches to a dome snap under each breast plate on the torso.  For the snaps in the mesh suit, I used a little circle of denim as a backing washer, to stop them pulling through the mesh. 
The cape mounts through slits in the torso, above the clavicle plates.

The finished cape… kind of…

One thing I did notice when it was finished, is that of all the panels, which were facing in different directions when I cut them out, there is one panel that when laid flat, reflects the light differently. I am not sure why only one was like this, as I had expected them to all look slightly different because of the angles they had been cut from the bolt of cloth. But when it hangs behind me, this is not really visible. If I do find that it bothers me, I will just get another 2 m of fabric and make that panel again, rotating the fabric before I cut, to see what angle reflects the light the same as the other panels.

This new cape is long enough to drag on the ground a little. I will trim the bottom edge to suit my height (170cm) after I have worn it a few times. This photo of my old cape, shows that I kept the scalloped bottom edge just off the ground. I personally would not recommend going any longer as even at this length I still stand on the bottom of the cape when I climb stairs. But as I test out the new cape, I will make a call on the length that I want.

Again, a photos of my old cape: From the front, the cape still hangs in a low profile… but when the wind catches it or I jump off something, the billowing volume of the cape is clearly visible.