You can thicken ink with isopropyl alcohol. But not too much, it will turn the ink into this crusty shit.
But then again, that only happened to me with a kiwi shoe polish + brake fluid combo.
Stamp pad ink is okay, I added that to my ink combo to restore some darkness when I fucked up my ink using some stock bingo ink.
For an extremely poor kid with a Giant's and Walgreens near by, what can I rack to make some decent ink? I already got acrylic paint markers for days, and I can just rack some more kiwi polish if needed, but I want to vary my arsenal and see what has potential.