Sure, it’s been lovely and warm, even hot recently. But cold weather is coming and if you’re interested in getting (inexpensive) community-built window inserts for your home, you’ve got to move swiftly to sign up.

Why would you do this? Using window inserts (two layers of clear plastic tightly wrapped on pine frames with foam weather stripping) can save you up to 20 percent on fuel bills, according to experts, and they cost a lot less than storm windows – especially if you connect with the nonprofit, Rockland-based Window Dressers, which builds them for an average of $25 each. If well cared for, they can last up to a decade.

The catch? You have to help build them. Which is only a catch if you object to learning new skills with other sustainably inclined people in your community who are trying to save money while reducing carbon pollution. Window Dressers is putting on 27 builds across the state.

Here’s how it works. You put in a request at the group’s website, windowdressers.org. Don’t have a computer? Call the customer service line 596-3073. Either way, specify which group build you’d like to participate in. Laura Seaton, the director of community builds for Window Dressers, will contact you within a few days and assign you to a build near you. “Then they are contacted by a team of trained volunteers who will come and measure,” Seaton said. They use laser measuring devices for precision. “We guarantee that they will fit.” They’ll also tell you how much the inserts will cost.

Builds are still being scheduled for the greater Portland area, starting with one for the Buxton/Gorham area in November. Seaton said the deadline to sign up for inserts to be built at that one is Oct. 2 (tomorrow). Another build in Portland proper, sponsored by the Portland Climate Action Team of Sierra Club, Maine, in partnership with the West End Neighborhood Association, starts Oct. 15 and runs through the 26th. It’s too late to sign up to get inserts, but you can still volunteer to help with the build.

Finally, sign ups close Nov. 1 for a January build at Allagash Brewing (becoming an annual event). Yes, it will be cold, but better late than never.