Creating printed circuit boards (PCBs) which aren't flat
You can create a non-square PCB simply by defining whatever shape you like for the board outline.  As for a non-flat one, PCBs just aren't made that way.

There are some alternatives that you could consider:


Flexible kapton circuits.  These the orange ribbons you see connecting things like LCD screens. They often have a few small circuit mount components on them, but they're not suitable for through-hole components.
Conductive thread.  You could use fabric with conductive thread for your circuit.  This is only going to be suitable for extremely simple circuits.
Multiple PCBs.  You could divide your circuit up into small flat pieces connected by wires.  This is probably your best option.  By using a number of flat tiles, you can approximate a curved surface.