For this game, you require number of patrols + 1 identical sets Lego. They must have two sets that are exactly the same is size, shape and colour of the blocks. You probably want at least 30 or more lego in each set depending on how hard you want to make it.
One leader builds a design with the lego in another room (or out in a hall). The patrols can send one person at a time to look at the model. They come back and describe what they saw to their patrol mates. Then another girl can go and look at the model. The patrol tries to build exactly what they see in the leaders model. The first patrol to copy the leaders build wins. Try to play the game more then once so the girls can try to improve their communication.
Variation: If you don’t have access to lego the same game can be played with other building toys or blocks. You can even use shapes cut of of felt or bristle board.