When we (Mostly Ed) constructed the bike the accent was on strength, simplicity, and git-er-done. Now that I have time to revisit I am trying to shave a few pounds off it. The rear fender was a large piece of steel that served as fender, tank support and chain guard. Very effective but weighty. I replaced it with a small steel tank brace, a minimum plastic fender and an aluminum chain guard. (All that is enclosed in a rear streamline fairing.)
The enclosed chain guard-tensioner was sandwiched in steel so I cut some panels out of it and used some balistic tough polycarbinate for an adjustment monitor window on the inner-back side. (The front, leg side, has a steel screen.)