Filament Colouring using Inkjet Ink

So I have only a few rolls of filament and wanted more colours. Searched and found a few thingis and even printed one of the designs.

All used marker pens to colourise the filament. Tried this and on my first attempt, while it did colour the filament, it was very "layery" and of course the felt tip got stuck in the hole and would not come out. Also the pens only inked a side and not very well. There was also colour bleeding because the pens left residue inside the plastic thingis.

I had s