To paint over ANY surface, without sanding, use a product called 'ESP Easy Surface Prep', available at hardware and paint shops. Wipe on, wipe off and paint in 90 minutes. Works well over enamel paint , without having to sand. SAVES HOURS of work. It was recommended to me by a professional painter.
This classic garden arch has just six parts and can be built in less than a day. Create a gateway, frame a walkway in a hedge, or make it part of a trellis or pergola. I kind of think Rachel was looking for something like this.