When attaching any type of molding, you will probably want to hide screws or nails. If the molding is to be painted, filler can be used to cover these holes. Stainable filler is also available for natural wood finishes. For prefinished moldings, or where expensive hardwoods have been used, the most professional finish is achieved by plugging the holes. This involves filling the hole with a piece of wood that matches the molding in appearance and is thus almost invisible. The technique is shown below; you will need a drill plug bit and the basic toolkit.
Once a screw has been inserted, apply wood glue to a dowel and insert it into the screw hole (Image 1).
Drive the dowel firmly into place with a hammer (Image 2). Wipe away any excess adhesive.
Use a block plane to smooth the cut end of the dowel (Image 1).
The plugged hole will now be almost invisible (Image 2). Repeat on all screw holes across the surface.