Conductive filament exists, but it takes more than that to 3D print something like a circuit board. The main issue is that traces made from conductive filament are basically resistors; they don ...

The copper lines (sometimes aluminum) on a printed circuit board (PCB) that allow electricity to flow between electronic components. See wire trace. THIS DEFINITION IS FOR PERSONAL USE ONLY.

But is there is really no greater sin than a 90-degree trace on a circuit board? This conventional wisdom of eschewing 90-degree traces is baked into everything we know about circuit board design.