"That does work great. But, if you can only spray a couple of times, you can also brush on the rest of the coats. Gives it an artists look too as well as going on a bit thicker, but be careful not to create runs. . Also, you can also use…"
"I do a lot of artwork for a Nature Centre. One thing I do use is the clear coat exterior Varithane to coat projects. The SPRAY version which is also water based. This can seal the paint and the box. Since you used a marker, I would not use…"