I was not content with merely mixing the contents of bottle A with bottle B. No..that was tame, and rather boring. I did have two largeish ziploc bags filled with international sized ink cartridges. One set blue and one set purple.
I did not have a knife or scissors or other cutting device for opening said cartridges. For one thing I wasn't sure that that way wouldn't make as big a mess as the way I had planned. For another..I didn't have them, and there was no sense letting something as small and mundane as the lack of proper tools to get in my way.
I do have a pair of jewelry pliers. And I had a bottle of dip pen sienna ink. I don't like sienna. It looks like the little brown that couldn't so I dumped it out and washed out the bottle. And then I spent some constructive time with the jewelry pliers and the empty glass bottle, squishing cartridges until they burst.
When you squish a cartridge inside a bottle, there's a lovely explosive spray. It is rather pretty for the first ten or so times that you do it. After about the twentieth time you begin to notice that your fingers look as if you're the last living survivor of the Great Grape Stomping Massacre. You've got speckles on your stomach. Your white tee is laughably not. However, it's also not artistically daubed enough to go well as a sort of tie-dye. In fact you look a lot less like Jackson Pollack's younger cousin than you do a ravenous bear in a berry patch. There will be ink everywhere. There will be ink in places that you cannot reach.
There are also some truisms about ink. Waterproof ink *IS*. Especially and ONLY in places where you really wish it wasn't. Washable ink isn't. See water proof ink for the reason. Erasable ink isn't either. It is both water proof and wear proof but only when soaked into the finish of your computer desk.
After a while of doing this you will accumulate a lot of squished cartridges. Don't try to recycle them. People will just laugh at you. I mean those people that aren't already laughing at you for the mess you've made. Throw them away. You will also have a half full bottle of ink. The temptation to work through ALL your cheap cartridges and fill the bottle to the top is strong, but resist. The explosive force of the bursting cartridges will force more ink out of the bottle than you will put in. Stand pat at half way. Be strong. Your wallpaper will thank you.