[ Sen frowns for a moment before making her way to one of the blackboards and waving B52 over. She picks up a chalk and draws what seems to be a layered gobstopper and adds a fuse. It's rudimentary, but she hopes it suffices. ]

You kind of want to use a material that can release a lot of heat or gas at once. Usually that's gunpowder, but I don't think we have any of that here....