I use a Cross with their refillable ink cartridge. Couple of bottles of a beautiful dark-blue (blue-black) hue of ink from Japan. And when traveling, I conver

I use a Cross with their refillable ink cartridge. Couple of bottles of a beautiful dark-blue (blue-black) hue of ink from Japan. And when traveling, I converted a medicine losenge tin (think similar to Altoids) to hold a possible spent refillable ink cartridge without it getting too messy - The bottles of ink do not travel well, potentially creating quite the mess. Instead, once it runs out (dozens of pages of notes later) I switch to disposable cartridges of blue-black ink. And I keep a .9 mechanical pencil handy, just in case I am really prolific and supply stores are not easily found :)