I will often use marker for incised plate printing with my younger students....with mixed results.
After trying the Sargent Solid Tempera Paint Sticks, I don't think I'll ever use markers for this again!
There are different brands out there (DO NOT USE THE DOLLAR GENERAL VERSION..TERRIBLE!) of the paint sticks, but I'm a huge fan of Sargent!
(I did switch to blue from the original purple above!)