For enduring ideas, you want enduring ink.
BLACK LRG 12/PK CHISEL TIP MARKER, 12PK.This Large Marker delivers permanent ink in rich colors so your notes are conveyed with authority. The ink is low-odor and certified nontoxic. The chisel tip allows you to vary the width of your strokes, from thin lines for small writing spaces to broad ones when you're commanding the attention of a room.