The following is an excerpt from MAKERS: The New Industrial Revolution, by Chris Anderson, published by Crown Business. It is released October 2.

Lego, as a family-oriented company, has some rules about guns.

With few exceptions, it doesn’t make twentieth-century weapons. You can go farther back into history and have Lego swords and Lego catapults, but not Lego M-16 automatic rifles or rocket-propelled grenade launchers from today. Or you can go forward into fantasy and have Lego laser blasters and plasma cannons, but you can’t have World War II machine guns and bazookas.

That’s a perfectly fine policy for Lego, but the consequence is that it tends to lose its customers around the age of ten, when they go through their war phase. That included Will Chapman’s sons. In 2006 his youngest one wanted to replicate a World War II battle in Lego and was disappointed that he couldn’t do it with the Lego figures he already had.

That would have been the end of the story, but Chapman is a Maker. In his Redmond, Washington, basement he has a small CNC mill and he knows how to use 3-D CAD software. So he started designing some Lego-sized modern guns. And because he could, he actually fabricated them.

To do so, he first sent the files to his desktop CNC machine, a Taig 2018 mill that costs less than $1,000, to grind the mold halves out of aircraft-grade aluminum blocks. Then he put the molds in his hand-pressed injection-molding machine, which uses regular propane like that for a backyard barbecue to melt plastic, and a lever like a water pump to force it into the mold. For the plastic he just used spare Lego blocks, to use the same ABS plastic as the real thing.