I made a blank lid for the launch controller so people can personalize it. For the final version I created a 12.2mm hole for a toggle switch with safety cover, a 16mm hole for the push button switch (normally on) to launch. Also 5mm holes for the banana plugs going to the alligator clip leads connecting to the rocket. The LED hole is also 5mm.

I reconfigured this and got rid of the screw holes I went with 10mmx2mm magnets printed into the lid and base. Not very sturdy but it's ok.

Here is the tinkercad link to both files. Please make a copy and do not edit the original. It allows you to ungroup all of the objects and make changes.

About the wiring:
Keep in mind that Red in DC is positive!! I forgot this and it took me a while to figure out why things weren't working for me.

I purchased or had lying around the following:

1. Rocker Toggle switch with LED 12V. I believe 20A rating but 15A would be fine as well.
2. Banana Plugs both male and female.
3. Momentary Push button switch (normally open)
4. 12V LED. This is for continuity check when the alligator clips are connected to the ignitor on the rocket.
5. 1k resistor. You don't want the ignitor to go until you push the launch button. This limits the amperage to just enough to light the LED but not enough to launch the rocket.
6. 20G wire but really doesn't matter much. Short runs. I did use 18G or maybe even 16G speaker wire going from the controller to the ignitor. I had it lying around so not completely sure what gauge it was. it was also marine grade but that's not that important. It just happened to be I had about a spare 20ft of it lying around.
7. 5800mAh 12v rechargeable Lithium battery. This battery was overkill I think because when the launch button is pushed the ignitor immediately ignites. There's no hesitation. Pretty sure I could go all day launching rockets with zero concern.
8. 5.5 x 2.1mm 10A DC power jack socket threaded. This was flush mounted on the side of the controller so I could recharge the battery without opening the box. I may glue the box shut.

You will find lots of diagrams out there for building a launch controller with a continuity check. But you can probably figure it out by looking at my pics. If your continuity LED doesn't work try switching the wires of the LED based on how the power is coming in. It does make a difference.

Lid:
https://www.tinkercad.com/things/lvtOtakFdZ8-lc-lid-share?sharecode=sOdqppfDPsiEMtEqQVhBjslytiSWA13-ASP7ZYpOqVo

Base:
https://www.tinkercad.com/things/kRulzaaY7Uy-lc-bottom?sharecode=W5hy4PFGpiugxd_xHgoistiWNSMaBCd20MjxU3zXvXs

Thanks for the great start Owen1975!!