A pediatric anesthesiologist at the University of Mississippi Medical Center has figured out a way to build a makeshift ventilator for less than $100.

Dr. Charles Robertson used a garden hose, electronic valve and a lamp timer to create the machine, now being called a Robertson Ventilator. The ventilator can be made in about 20 to 30 minutes; nearly 100 could be made in one day by four- or five-person teams. Robertson presented the ventilator at a press conference on Tuesday. “The brain behind the thing is actually a lamp timer,” he said. “It’s not fancy but it works. This would be available as a last resort if the numbers increase as we think they might.”

As of Tuesday, UMMC staff had already made 170 Robertson ventilators. UMMC has also applied for an Emergency Use Authorization from the FDA to use the machines for patients if needed.