Hit your local fine art store for some Gold's acrylic clear coat. it comes in several viscosities and the thicker ones can be blended/moved to produce those thick brush in paint textures. one note, I find it to be slightly tacky even after a long dry time, don't stack coated things together or they glue themselves just enough to mar the surface. this stuff is specifically made to add volume to paint so it'll really give you that stand up texture and it looks wet when dry (looks semi opaque when wet - don't freak).