[dreamcompiler]

Or you could skip the aerogel entirely and use a hard, incompressible shell and pull a partial vacuum inside. Of course we don't currently have any materials both strong and light enough to do that. Neal Stephenson proposed such vehicles made from thin shells of diamond in The Diamond Age.

[rini17]

Right and when one shell breaks, the shrapnel breaks the other ones and everything around:)

[dreamcompiler]

Well, they'd implode (the gas inside is at a partial vacuum) so most of the shrapnel would travel inward. But yeah, diamonds are hard but not tough. It's possible that a kid with a BB gun could shatter such a craft with one shot.

But they'd certainly look cool.