Currently, I ride a velomobile; to be more specific, a Mango Sport manufactured by Sinner Bikes.
The race cap (white hood on top of the velomobile) is a nice, optional feature, it keeps me warm in winter and dry on rainy days. The cap has a hole on the left and right side, respectively, which provides a surrounding view and passes the traffic noises to my ears. They must be kept open during the ride, but don't hinder rain to get into the velo if it stands still at the parking place. Because I drive to work with the velo every day and my company doesn't have a roofed car park, the velo sometimes collects water inside on rainy days.
I found out a simple solution for this problem by using two plastic, acrylic glass plates (Plexiglas) and eight super magnets.
I cut out two acrylic glass plates with an appropriate size and mounted two super magnets on each plate. The remaining magnets are placed in the hood interior such that the plates are held in the right place. In both cases a simple glue gun keeps the components together. One of the plates was a bit thicker (I used spare parts) and did not match the slightly rounded shape of the race cap; a bit of heating fixed this problem quite well.
This set-up has the advantage of using no hinge or any mechanical stuff which might break during the ride. A placement is easy and fast: just cling the plates to the side, the magnets will do the fine adjustment.