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 them together – or you could make an FPC. Flexible ...

Sure, you can make flexible PCBs like the kapton-backed ... [Rehana] used a tool called svg-pcb to design the board. This is an open source toolkit that lets you design PCBs by describing them ...