A relatively new type of weapon is flooding the streets.

It’s untraceable, invisible and you can make it in your own home. In this Virtually Rick we delve deeper into the murky realm of “Ghost Guns.”

So what is a Ghost Gun? It’s a firearm that doesn’t have a serial number, the unique identifier that allows law enforcement to find the owner, similar to the VIN number of a car.

Ghost guns are basically invisible until they appear at a crime scene. And it’s happening more and more, they’re being used in high profile mass shootings, including 2013 in Santa Monica, and others around the country.

Guns have always been available on the black market but getting them was risky and problematic. Now, thanks to the rise of 3D printing and easily accessible computer controlled drill machines plus bitcoin and credit cards, gun parts can be purchased online and easily assembled.

Laws past and present make it legal for you to make your own gun as long as you don’t sell it, but you have to register it and get a serial number from the California Department of Justice.

Hmm, can you spot the loophole? More of that in a bit.

At the core of the problem is one specific part, known as the receiver. It’s the heart of a weapon like the AR-15, a light-weight semi-automatic rifle, meaning a gun that ejects and re-chambers a new round -- a bullet -- after each pull of the trigger.

The receiver can be bought easily & legally online or in stores as long as it’s an 80 percent receiver, meaning 80 percent finished.

With a bit of know-how and YouTubing from multiple online sources, small holes can be drilled into it, making it seriously easy to then assemble other parts of the rifle around it.

You suddenly have an unlicensed, ghost gun on your hands.

Because of this frankly insanely easy process, it’s possible to turn a sizeable profit making them. And ATF agents have seized large numbers of Ghost Guns because known felons aren’t allowed to legally purchase guns, so they’re making and buying ghost ones instead.

And because they’re relatively cheap to buy and make, the sale can mean thousands of dollars profit. So if you scale up production - that’s big money, and a wholly new and massively profitable deadly underground weapons market, which exactly what's happening right now in our city.

So let me get this straight. You can now make your own gun cheaply, easily and it’s OK for you to keep it. But the law says you have to go and get a serial number, so they know that you have it.

Now doesn’t that defeat the whole purpose of having a ghost gun in the first place?