Spend a few minutes planning out the shape of your LED matrix.  I have fairly narrow wrists and wanted a very sleek design, so my matrix ended up 16 pixels long and 5 strips wide.

I made my matrix rectangular just to keep the project a little simpler, but this code will work with any shape you want to create, with a little tweaking in the Processing script setup.

 You can also use a premade Dotstar matrix.  However, a gauntlet will need to move quite a lot and these matrices are bendy but not unbreakable.  I found that creating my own matrix was a little more cost-effective and flexible in terms of size and shape.

Slide your dostars out of the silicone sleeve and carefully cut each strip to length.

I found it easiest to use the "sacrificial pixel" method: instead of cutting through the middle of the teeny tiny solder pads, cut so you leave full pads on each end of your strip.  

This will render one pixel out of each section useless but makes the whole project much easier to assemble and a lot more robust in the long run (the full pads have more contact area for solder).

Lay out your strips so that the bit-direction arrows are all pointing the same direction.  

Turn the strips over and tin each pad on the back of both ends of all strips.

Find the "in" end of your first strip and solder a 4" wire (or whatever length your design demands) to each of the 4 tinned pads.  

Connect the other end of these wires to your Feather:

• Dotstar D --> Feather #11
• Dotstar C --> Feather #13

Connect the power wires to your battery extention cable.

Turn your Feather on and make sure the LEDs in this first strand light up.

Next, solder carefully measured wires between the "out" pads of your first strip and the "in" pads of your second strip.  Solder them in the direction shown to avoid any wire loops or places that could get pulled.

Repeat with your other strips, testing each strip as you go.  Once you've got the whole matrix built, cover each wire joint with hot glue to secure it in place.

Turn your matrix on and flex it back and forth a bit to make sure all your solder joints are rock solid.