STEVE INSKEEP, HOST:

Each year Lego turns out 19 billion plastic bricks, figures and gizmos for building things. But for serious Lego collectors, 19 billion is not enough - which brings us to Seattle area resident, Will Chapman.

As NPR's Wendy Kaufman reports he's part of a small but thriving network of people making Lego compatible parts.

WENDY KAUFMAN, BYLINE: Lots of good business ideas have emerged from kids' play. Will Chapman could thank his youngest son. At the age of nine, he wanted to know all he could about World War II and was using Lego toys to act out history. But his son was stymied - he couldn't find all the pieces he wanted.

WILL CHAPMAN: So we said well, let's try to make them out of Lego bricks. You can't. You can't make the weapons and the helmets that he was looking for with the parts Lego has. So I said let's try to make them ourselves.

JENNIFER CHAPMAN: I just assumed it was another one of his creative adventures.

KAUFMAN: That's his wife, Jennifer Chapman.

CHAPMAN: I really had no idea it was going to become a business.

KAUFMAN: But one thing led to another and Will Chapman would soon give up his day job as a software engineer and become an entrepreneur.

As soon as you walk in the door of the company known as BrickArms, you know you're in the lair of a Lego addict. Just about everywhere you look in this modest industrial space - occupied by just Chapman and his wife, you see blank Lego pieces, such as heads and torsos in multiple colors.

You see display cases filled with authentic Lego mini figures, along with Chapman's own creations, like this World War II soldier.

CHAPMAN: He's got a bandolier with ammunition pouches, he's got a canteen, he's got suspenders.

KAUFMAN: Pretty amazing, considering the figure is only about an inch and a half tall. But there's more.

CHAPMAN: He's got a T-shirt and a little bit of his neck showing, and on his back he's got a medical kit, he's got a utility pouch, he's got a couple of wrinkles, showing how that shirt might look if it were made of material.

KAUFMAN: You won't find anything quite like this that's made by Lego. Christoph Bartneck, who's written extensively about Lego and compiled a catalog of its mini figures says Lego makes weapons and fighters from the Wild West and the fantasy world.

CHRISTOPH BARTNECK: But anything from the great wars or modern warfare is something they do not do.

KAUFMAN: He says it's a decision based on the company's philosophy about what is appropriate for Lego play.

BARTNECK: And war themes don't really blend in there very well, and then the secondary market, of course, satisfies this.

KAUFMAN: Now you might think Lego would try to sic its lawyers on companies like BrickArms, but it doesn't. And while Lego doesn't publicly endorse them, it acknowledges they offer something some of its fans want.

Will Chapman is thus free to turn blank Lego pieces, which he buys in bulk online, into custom figures. For his weapons, which typically retail for about a buck a piece, he uses computer-aided design programs and then makes a prototype using what's essentially an enhanced hobby-grade machine.

(SOUNDBITE OF MACHINERY)

CHAPMAN: I take a blank of metal...

(SOUNDBITE OF CLANKING)

CHAPMAN: ...clamp it in; set my bits. And then when I am ready to go, I turn on the spindle.

(SOUNDBITE OF SPINDLE WHIRLING)

KAUFMAN: Chapman has taught himself a lot about design and the manufacturing process, but he's quick to say that advanced technology and software allows him to do things he couldn't have done just a few years ago.

CHAPMAN: I'm constantly amazed that one person can do all this, that I can create something that didn't exist. Who gets to play with lasers and CNC machines and injection molders and fancy printers? It's the most fun job I've ever had.

KAUFMAN: Will Chapman says, while he's not getting rich at BrickArms, he's doing just fine.

Wendy Kaufman, NPR News Seattle. Transcript provided by NPR, Copyright NPR.