if you're worried at all about putting the fans further apart you can pick up wire from a hardware store.
Also, when putting a fan to a power adapter, test the lines by touching the fan's wires to the adapter's wire. This also tests the fan's blow direction. This way you can figure out which wire you need to be hot, while maintaining the fan's natural blow direction. (at least thats what I did and it worked for me... no guarantees here haha. i don't know every variable of your setup)
Also, if you have a soldering iron, you can create joints between the wires with a bit of solder and cover them up with electrical tape. a little more secure/solid than using caps.
If you're working with a CPU fan and a power adapter, check out:
https://www.rollitup.org/do-yourself/8402-how-turn-pc-fan-into.html