If you want to have a lot of components within a cramped non-flat area, you could carefully design a multitude of stuff FR4 boards and connect ... a custom-made flexible PCB.
As it turns out however, you can also make flexible boards using regular PCB material: check out [Rehana Al-Soltane]’s Flexible Crown PCB, a project she did as part of [Neil Gershenfeld]’s ...
Absolute EMS, Inc., a four-time award-winning EMS provider of fast turnaround, turnkey contract electronic manufacturing ...