Portal Sandalias

Does anyone at all know what I can seal this with so the paint will not wear so easily?

I've tried mode podge from the plastic jar and clear nail polish-both very messy/wear off easier than the paint itself. I need something skin friendly .___. since these will be in contact with feet and what not.

Elmer's paint markers on sandals


Aperture, portals, companion cube loving - Valve