Authorities in western Iowa are still looking for a fourth person in a drug-making ring busted this week in Montgomery County. Sheriff Tony Updegrove says they were operating a “mobile meth lab,” set up with materials that are easy to pick up anywhere.

Updegrove says it doesn’t take much — at any discount store he says you can buy pitchers, utensils and cheap plastic items that are needed. The only difference with a “mobile” meth lab is that drug-makers, knowing the process has a strong distinctive smell, will mix up a batch and drive around with their works in the trunk of a car out on the open highway. That way nobody’s likely to notice the smell and call police or a local fire inspector.

Sheriff Updegrove says it’s no safer than a meth lab in a building, and one reason is the flammability of the materials. He says the chemicals are very volatile and with a car jarring around all the cheap household items used to rig up a homemade drug lab, they can jostle, spill the chemicals, and even cause a violent reaction or a fire.

Three people from Red Oak were arrested Sunday with what the sheriff says was a mobile meth lab, and they’re still looking for 25-year-old Christopher Bowers, who authorities say travels between Red Oak and Shenandoah.