[spacechild1]

> I aim to let users combine individual parts into modules, as well as customizing their visuals.

Have you heard of Pure Data or Max/MSP? :)

[leftyspook]

I've heard about Pure Data but here aim is to a) emulate the feel of a real rack (to which end I am rewriting the UI from scratch) b) relatedly, aim is to be friendly to non-programmers, cause all musicians I know can't use a computer for more than opening a DAW

[spacechild1]

Also check out Automatonism (https://www.automatonism.com/), which is actually built with Pd.

[johnofthesea]

Or NI Reaktor.