Internal controller wire length problem for RPI portable

[Aulmon]

To skip the fluff, jump to the bolded paragraph

Hey folks, in the middle of my first raspberry pi build, and my complete lack of knowledge has given me issues at every turn. At the current time, I've overcome all of them but one. I have this thing fully laid out, finally. It used a gpio screen, a cannibalized snes USB controller, and a RAVpower battery bank as the source. The issue is with my current design, and I can't seem to figure out a better one.

It's in two separate pieces. The top piece is the screen and the pi itself. The bottom piece contains the controller and battery bank. Everything is modular and ready to be built except the controller. It's even made so it can be plugged into a television and outlet instead of the portable controller/battery setup.

If you refer to the picture, the template I made is on the bottom, and the battery pack + controller is on top. My plan was to place them in the enclosure as they are, one on top of the other, except the wires going from the main board of the controller to the triggers are far too short to wrap around the battery. I've been forced to redesign this thing many times for many different reasons, mainly because of my lack of tools, but this is the worst yet. See, I can't solder any of this. I'm working with what I got, and I doubt I can get the money together for any expensive tools. I'm going to the hardware store tomorrow, so make sure it's a solution i can solve from there (specifically, a home hardware in Ontario, Canada)

Brainstorm, be creative. There may be literally nothing I can do but buy a soldering iron. Feel free to say as much, but don't be rude about it. I've done a fair amount of research, but without much success. The closest I found were some weird 3m clip things, but they aren't available locally. So please, is there an easy way to lengthen those tiny wires? Tell me step by step, since I'm completely unfamiliar with any of this. Also, how do I snip the jacket off the wire without damaging it?