In this section, we'll resize the PiCable so it's more manageable once installed inside the case. Its some what optional - you can skip it but if you find space too tight when closing the case, you may want to resize the PiCable.
The stock ribbon cable is 152.4mm(6") in length, but I've found shortening it down to 108mm is just the right fit for the length we need.
Measure, Mark and Cut Ribbon Cable
Use a pair of calipers or measuring tape to get the desired length and mark the ribbon cable - Tape, marker or otherwise.
With the cable split in two, set aside the longer end and keep the short end handy - we need to remove the connector from the end of it.
Peel Cable from Connector
With the top removed from the connector, carefully peel the ribbon cable from the connector. You should be left with the top part and the female connector. You can discard the ribbon cable.
Unless you're incredibly strong, you won't be able to press the top piece back onto the connector because it's hard to puncture the wire with the pointy teeth. The easiest way to do this is to use a rubber mallet to smash the pieces together. I recommend doing this on a hard surface (like on the floor) while holding the connector in place. Tap the top piece in sessions as straight as you can and be careful not to mash your fingers in the process. If all goes well, the teeth from the connector will puncture the ribbon cable and close the two pieces back together.
And there you have it! A shortened Raspberry Pi Ribbon Cable. Bit of a hack, I know - But it really does make closing the case much easier in when we're all done.