Next using the 45° miter box and razor saw, cut 45's on one end of each stinger, using a 72" straight edge as a guide, butt glue 2 stingers together to form a 72" stinger.

When selecting the stingers to glue together, select good pairs and glue the straighter ends together.

once you have 4 sets of stringers set that aside and let's put the firewall together.