When you pull out the pieces from the molds, in most cases they have air bubbles or holes. So my work consist in fill the holes with another material before paint them. I use epoxy putty or clay. I mix the two components and wait for around 15 minutes before use it.
Later I fill the holes with the clay. Usually I do this two or tree times per piece in order to get a clean piece, but It is impossible to fill them all. This step requires too many patience and time. Once the epoxy putty is cured, I use sandpaper and water to sand the piece as you will see in the following video
The next step is to sand the pieces with another sandpaper. This one is more delicate and will allow my to polish the surface of the piece to get that smooth finish. You will feel it as soon as touch it. If you don't do that, you will see scratches under the paint.
Same procedure is used to complete the Grappling Hook Pouch, but requires more rounds of filling and sanding than the hollow ones. The next step is paint them. You will see how I painted them in the next status report. May the Force be with you!