Well typically you get a glossy finish on the surface between the mold and the part. So in your case, that should be the inside of your enclosure.
I usually 3D print my enclosure negative molds, sand it, bondo it (if I want a very smooth mold surface), apply a gel coat, then 7 layers of release wax, and 4 or 5 layers of PVA. Then will start laying my cloth. This will lead to a shiny surface. But it is quite time consuming and the gel coat, wax, PVA, mold plastic, and bondo make this quite an expensive part if you only make one.
The mold is very shiny and the finished product will reflect this finish. The vacuum ply will leave the part dull.
Here’s a simple fiberglass part from another mold