Slim 18650 Case

I designed this case in order to make my 18650 2s packs neat and safe, but also as small and light as possible.
Here's a few simple pack assembly instructions, I will try and update this with some photos once I've had a chance to assemble another one.

Pack assembly instructions:
Step 1:
Take your two 18650 cells and solder a 20mm length of wire between the negative (-) and positive (+) terminals at one end of the cells. Be careful to make sure that the wire is well insulated on the positive end as only the centre of the pack is positive. If the wire is allowed to make contact between the centre terminal and the outside of the cell you will have a fire on your hands.
Step 2:
Attach a smaller wire to either end of the joiner piece and run it up the middle of the cells and leave it loose at the other end. This will be used for your the middle lead of balance connector.
Step 3:
Slide the two cells into the main part of the case and apply a drop of glue if required (most brands s