Thanks both of you for your replies, judging from both your posts i might have underestimated the difficulty !
I'm not against using a PCB but sadly my project simply won't allow me to, here is the project with more details:
I have a 1/24 die cast police car to which I want to add a whelen justice lightbar on the roof (so the height is barely around 1,5 or 2 mm), as well as lights on the headlights, taillights, and grill lights.
I'm more than open on suggestions on the best approach to proceed !