爷爷的工棚里堆满了各种古怪的装置，有些连他自己都忘了是干什么用的。

Grandpa's shed is full of weird ___contraptions, some of which even he forgot how to use.

他设计了一个用橡皮筋和纸杯传递信息的复杂装置。

He built a ___contraption with rubber bands and paper cups to pass messages across the room.