VCV Rack: is an Open-source virtual modular synthesizer.

Rack is a simple and easy to use synthesizer; you can simply add rack components aka wave generator, filter, delay, echoes, and many other effects via dedicated plugins, as easy as “connect a plug” in a physical rack, to generate your sound and music.

Result (below) is really realistic, you can also configure cable opacity and tension and zoom level, if you have busy screen or need more room.

Available for all platforms.