Re: inks for technical AND Nib Pens /multi-media
For my technical pens I use Rapidograph Ultradraw, a black ink that dries waterproof. I know that Rapiodgraph does make colored inks for their pens, but I have never used them and I don't think they are waterproof. I have never seen the colored Rapiodgraph inks in a store, but if you look on-line you might be able to find a source.
I fear you are not going to be successful finding colored inks that you can use in technical pens and that are also waterproof, the combination tends to not work. I suppose you could try thinning acrylic inks and trying them, but be prepared to ruin some tips/pens so it could be a costly experiment. I also doubt that you will find an ink that will work with all three types, nibs, technical pens and airbrush as they all have different requirements when it comes to flow and/or consistency. But you won't know until you look, good luck.