We found a block which we used to place the hand on, it had a whole in the top which allowed us to hide most the wires inside the block along with the mac. The projector was then placed in front of the handprint so people would not block the projector. We tested it for a final time before the deadline to alter the readings and make sure it worked correctly.
This was what the setup looked like.
The only issues we had were the arduino was too close to the mac so the readings were automatically too high, this was solved by putting the arduino into a box and the mac was placed on a box under the block we had.
Another issue was the hand was quite hard to see in the dark, so we needed to find a way to light the hand so people could see.
We also drew an image of people holding hands to try and encourage people to do the same.