I'm using Pilot Jumbo and what a sturdy marker it is. The nib was worn out so I ditched it and plugged with some felt and Garvey & Marsh-T mix(couldn't find Pilot refillable.). So far, so good.
I just got Marsh-T and Garvey Purple. I'm going to test out the ratio and go from there.
Marsh-T looks quite thick. Is it possible to add nail polish to thin out a bit?