Soni Paint Marker Slim (Fine Plastic Nib) 3.05mm - Gold. Soni Paint Markers feature fast drying, oil-based ink that is formulated to adhere to all surfaces, such as metals, plastics, glass, ceramics, and wood. The ink is also water resistant and lightfast, allowing these markers to be used indoors and outdoors. Once the ink has been applied to a surface, it will not fade or wash away.