Many Cozy builders made their rear armrest different from the Plan. Typically, they were made in a single piece and removable as well. I decided to follow...
Making a paper template to help fit the top armrest foam against the fuselage sides seems to be the easiest way to go. The vertical side piece is pretty straight forward - just have to get the angle at the ends correctly. The picture to the left shows how I 5-min. epoxied the top and the side wall together - making sure they are at right angles!
The bottom side piece has always been difficult to fit. I decided to 'hang/drape' a real thin tracing paper along the bottom edge of the side wall. With the paper held against the fuselage, I traced out the shape of the bottom side piece. Then I removed the tracing paper and used it as a template for cutting the 3/8" foam. The next step was to shape the foam edges against the fuselage for a snug fit.
Here's a picture of the completed left arm rest (not glassed yet). I repeated the same for the right arm rest. It has been rather cold in southern California for the past few days (~40oF), so I decided to wait a bit before any glass work. I decided to proceed to the next section for now.
Warmer days finally arrived. I took the opportunity to glass both the inside and outside (2 BID outside and 1 BID inside per Plan). However, I changed the glassing sequence with the outside first because I can control the shape of the armrest easier during cure.
I trimmed the edges of the rear arm tightly with ~1/16" of lip at the seam. However, I left 5 small tabs for holding the rear armrest in place with sheet metal screws (per Plan).