When applying fiberglass and resin, typically it is important to lay it all down and incorporate it into the surrounding laminate.  However, there are limitations to this.  The fiberglass does not go around sharpened 90 degree corners.  The fiberglass strands have a minimum radius, and making the attempt will result in either fiberglass sticking up, or a large air bubble and poor surface result.

Often the best alternative is to let it stick up and trim it.

to be trimmed

The photo demonstrates the laminated areas where the extra fiberglass was allowed to hang off the edge of the wetout area.  This can be trimmed later.  Depending on the timing, it can be easily trimmed with a razor-blade knife.  This is attempted before full cure. This is what I refer to as “wet trimming,” as the resin is in the cure cycle so it is still sticky, and not a liquid but solid enough to be cut.  It requires monitoring of the cure progress to get the correct timing.

After full cure, this trim work will require a saw or grinder.  It tends to be messier and more labor-intensive.