"About got the top half ready for fastening. My method is to use tape to define the cut line, I put a strip on the firewall even with the front edge of the firewal (Photo 1l, then lay the cowling over that, and put another strip of tape on. In photo two I cut the tape at the edge of the cowling, its rough cut to shape. Then some dark paint on the cowling to make an even line where it whould be cut, and from then on it is as easy as removing the unpainted edge with tinsmips."
