LDCad 1.6 (win+linux)

[Roland Melkert]

I know this. But I want to add parts to my library during the build as I come them across, without shutting the prog down.

I think this is not possible. However, changing any model outside LDCad (in say a texteditor, good ol MLCad, LPub3D), including parts, should trigger a prompt reload.
Adding a part does not do this. I could be wrong though.

I'm sorry it is indeed not setup to detect/add parts to the library during runtime, it only reloads already known ones upon changes. Any addition to the library needs a restart of the program.