MINNEAPOLIS (AP) — A Minnesota man whose profile in Popular Science magazine sparked an investigation into his pyrotechnics has pleaded guilty to illegally manufacturing and selling explosives.

Federal agents raided the Brownsville home of Kenneth Miller in March, after the magazine article showed photographs of Miller shooting red flares off the hood of his pickup truck and packing powdered chemicals in a makeshift laboratory.

The Star Tribune reports that the 58-year-old Miller had previous felony convictions that precluded him from touching the highly combustible material used to create these devices. Miller was first convicted of a felony for conspiracy to make illegal explosives in 1986. A few years later, he was convicted of illegally possessing a firearm in North Dakota.