David Short organizes the window section at the Building Materials Exchange in Lisbon on Wednesday. Short is a volunteer who has a background in window-glazing and helps the organization on occasion. The nonprofit has relationships with several suppliers and receives misorders, mismeasured items, overstocks and discontinued products. It also accepts materials from salvages. The organization is always looking for volunteers, from unskilled cleaning labor and organizing help to skilled labor. Those interested in helping are encouraged visit the exchange website or Facebook page.