Copy a lego model without really seeing it
Lego (split into identical sets)
Make a model and place it in one room/behind a shield. Give each group an identical set of lego bricks so they can recreate the model.
Architects and Builders - so split the group into two roles, where the architects are the only ones who can see the original model, and the builders are the only ones who can make the copy. The architect(s) run into other room, memorise as much as possible, come back and instruct the builders how to do it.
Similar to above, but rotate one "spy" around the group, so one at a time, the spies go and see how to recreate it and come back and make as much as possible. (They can touch the bricks)