How can u carry a second face shield on a sport bike?

[Layton]

Space seems so limited and a bag or humongous luggage case are ugly. How do I make it work without it looking like crap

 

[CandidChris]

A tank-bag is your best option or a small backpack.

 

[fuzzy]

mount it on your spare helmet & hang that on the clip under the seat if the bike has one.
I assume you've a tinted shield & want a clear one for night use. Leave the tinted at home & buy a cheap pair of sunglasses & cut the arms down so they can be slid on inside the helmet

 

[dan]

Wrap it in a small towel and place it under the seat, over the rear fender support.
That's why I recommend a clear visor and sunglasses.