I fell asleep last night printing cases and keycaps so I scribbled up these instructions when I awoke. I'll set up a video once I figure out a proper way to set up a camera:
The first step is to bend the leads on the diodes as close to the diode as possible to still solder. The shape of the bends should not be far enough from the diode that the leads extend into the next row below. It is easiest to bend a group of five or so diodes at once with needlenose pliers before you remove them from their tape so that you don't have to bend the leads individually. The bent tail on the prong-side of the diode could also be pointed upwards and used as a handle to set each diode down into place before soldering and snipping it off. Don't bend the prongs on the keyswitches, though. You're also going to want to wrap the diodes more tightly around the prongs than the pictures show.
Once that is done, cut and strip sets of wires the same length as it takes to reach all the prongs on each column. 7 of which will have 3 soldering spots and 4 of which will have 4 soldering spots. If - is open wire and = is sheathed, then they should end up looking sort of like this:
After all the columns and rows are done, all that is left with wiring is to connect the switches on the ends of the rows and columns to each of the selected pins on the Teensy. The ribbon cable I have available does not have enough wires bundled for all 11 rows, so you can split between two sections. I like to do one bundle of 7 for the switches to the left of the Teensy and a bundle of 3 for the switches to the right. The connections work like so:
The case is welded together with a heat source and can be difficult to remove and replace the cover if the wiring is set up properly, so test it thoroughly before sealing it. To close it, set a soldering iron to 210 °C and gently press the tip into the four spots where you would like to place the feet, making sure to be close enough to the edge that the bottom case can melt into the top case. If you received the clear round feet I am testing, it should look like this:
You may also receive white square feet:
You may want to try lightly sanding and cleaning the base before adhering the feet.
It should be done now. If you want to fully seal the bottom case so you cannot simply pop it off and/or you don't want the loose seam, slowly and gently drag the soldering iron tip (preferably a flat one) at an angle all the way around the perimeter at the seam while holding the bottom case in place:
Here it is in action!