He was using materials that he had 'liberated' from a construction site.
Soldiers 'liberated' the hostages from their captors.
a 'liberated' marriage
(..) I'm optimistic. Good evening. Yesterday, I authorized a covert rescue mission inside the Capitol. I am pleased to announce that the Victors have been liberated! Let this day mark an historic change. With The Mockingjay and the Victors beside us, we have sent a clear message to the Capitol. (..)2014 The Hunger Games: Mockingjay - Part 1
(..) But I have some conditions. Peeta and the other Tributes, Johanna Mason and Annie Cresta, will be rescued at the earliest opportunity. If and when Peeta is liberated, he will receive a full and unconditional pardon. No punishment will be inflicted. And the same goes for the other Tributes. No. (..)2014 The Hunger Games: Mockingjay - Part 1