Adding New Bones/Attachments To Models

I see on the garrysmod wiki there are a few bone and attachment functions, I was wondering if there was ANY way I could possibly add another model to a weapon and save it as a new attachment/bone for that weapons model.

I have tried spawning the model I want to add as a bone at the position and angle on the weapon and parenting the model to the weapon but it does not move with the weapon at the same time the weapon moves.

Another way I was thinking I could do this is somehow use cam.3d to draw the model but I haven’t found any functions available for drawing models.

Can anyone point me in the right direction?