I am surprised that TFB has not talked about the Sub-2000. As far as I can search, not once.
So lets take a look at this neat little folding pistol caliber carbine. For those who are not familiar with this weapon, It is chambered in 9mm or 40 S&W. Kel-Tec makes two versions. Glock magazine compatible and another version that can use Sig, S&W, or Beretta mags depending on the magazine catch installed. But the most intriguing feature is its ability to fold in half for storage.
Hickok45 does a little review on the Sub-2000