Finish the front edge of the roof with two aged 1/16 by ¼ inch pieces of basswood. Glue them along the front edge of the plywood roof support, just inside the shingle line so that the shingles overlap them.
Glue in place any cross pieces you cut from twigs to form the roof support. There should be one cross piece between the twig roof supports and a piece which reaches from the main cross bar up into the peak of the roof to help support the peak. The other pieces are decorative and can be left off.
