If the routing and epoxying of the pieces is done before the glassing how do you treat those pieces when rolling fabric over it and adding then epoxying it?Updated 2 years ago

You would tape over the openings in the plastic parts and roll the fiberglass of the entire part as you would the remainder of the board. 

You would then fiberglass the entire board including the plastic parts. After the fiberglass has cured you can carefully cut the openings using a sharp razor blade or a rotary tool.