you can use hot glue, I did both of these markers with it, I mainly use rubber cement or clear fingernail polish as my mask for splashes though...
it does not make as definite of a line, though for those, that was not what I was going for, making hot glue perfect, if you are going for perfect lines though, hot glue is not the best of ideas, as it does not hold down tight in all cases, making for uneven masking.