Buy a Kiwi shoe polish bottle at any department or shoe store that sells shoe polish. Take the cap off and rinse all of the shoe polish down the drain. Rinse the bottle out thoroughly until there is no residue shoe polish in the bottle.
Buy Krink brand graffiti ink (see "References"). There are many different colors to choose from, but it's ultimately your choice what color you want to work with. Pour the ink into the empty shoe polish bottle. (Use a funnel if you're worried about spills.) There will probably be some left over in the Krink bottle, so save it until your shoe polish bottle is in need of a refill.
Place a marble in the bottle. This is what will mix the ink when you shake the bottle before an application.
Seal the nib back onto the top of the bottle. When you're not using the marker, make sure that the cap is tightly over the nib. To apply paint, shake the bottle (with the cap on), then press the nib onto a surface.