Before beer ever reaches a frosty pint glass, the hops in it are often dried. But it’s not so straightforward: once picked, hops may mildew if not dried within 24 hours. Dried too much, the quality deteriorates. At worst, the essential oil-containing crop can spontaneously combust during processing or storage.

A team of Virginia Tech College of Engineering students has now developed a low-cost drying solution for the finicky crop — and they’re providing it open source to growers everywhere.

Hops driers, called oasts, are like kilns for fresh, wet hop cones, which are harvested from perennial vining plants during a one-month harvesting season late in the summer. While large-scale farms often have access to oasts capable of drying thousands of pounds of hops at a time, the local growers’ options are slim.

That’s why, as part of a larger hops grant, the Virginia Agricultural Council funded a mechanical engineering senior design project at Virginia Tech to develop an oast capable of being powered with only 120 volts, built using off-the-shelf materials, and costing no more than $4,000.