One of you can see the model. The other has to build it, out of real bricks, from nothing but a description. Then you swap. The screen never sees your bricks and never scores you — it deals the models, guards the secret and keeps count.
Models are only ever built from what you tick, so both of you can lay out the same handful of parts.
Take these parts. One set each.
Same parts, both of you. Anything left in the tub is out of play.
Only the describer
Tap when the other one is looking away
How did do? You two decide — the screen cannot see your carpet.