Since you didn't state "taking it apart and making more isn't allowed" in the rules...
Scenario 1: I'm not a asshole.
I would immediately start disassembling it and reverse-engineer it for the schematics. I would then create more portal guns and patent them, and then I would make a startup shipping company that would use portals to transport goods almost instantaneously. My service would boast enormously low shipping rates, and since it uses portals: no shipping time. I would outcompete USPS, FedEx, UPS, DHL and all the other major parcel and postal companies in a matter of weeks, and I would possibly be the first trillionaire in the world. I would donate millions to charities on a daily basis, and I would pay off the U.S. Federal Debt in one lump sum. Everyone will be in my gratitude and everyone would love me.
Scenario 2: I'm a bit of an asshole.
I would just dick around and screw with my friends. Travel? Pshhh... Why fly or drive when you can just *be* there? I could pop in at my friend's house in Hawaii all the way from Texas anytime I wanted. I could do pretty much anything I wanted, whenever I wanted. I could create the fastest connection between my friend's computer and my computer, by simply running a ethernet cable from my friend's computer, through the portal, and to my router.
Scenario 3: I'm an asshole.
I would start robbing banks. Lots of them. Who can figure out a crime when the getaway vehicle... was never there? I could steal electronics, money, art, gems, whatever! You name it, I now own it. WYIM! I would quickly amass a reputation among underground criminal syndicates, and I would most likely become the leader of one. I would rule the US with organized crime in a matter of months, similar to Chicago circa 1920's. Anyone and everyone would answer to me, and the police wouldn't dare try to arrest me, 'lest they face the consequences of messing with one of the most powerful, wealthy, and influential people in the would, much less the US.
So, those are my ideas, got any suggestions?
