I would love to make velomobile myself, but currently don't have funds.
However for fairing I would consider WWI route, aeroplanes, they were made from relative light wooden fixture and fabric. Today you can get really light fabrics that hold wind really well, parachutes, all kind of gliders are made these days from such, it would need only light structure when pulled tight over that structure.
I have not looked price of such materials yet as I have been just playing around with thought, but for me that would be something tha would add least amoung of weight and it would be relatively easy to build too, also one might be able to make mechanism to open and close to get easy entry to vehicle too.
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