Wow, congratulations, Robert - you have made a lot of progress.
After finishing the Art Room puzzles, according to the walkthrough you should then go to the forge:
It is time to revisit The Forge. Go through the blue portal outside the Art Room and use the red disk to return to the West Tower. Use the yellow disk on the 3 disk balcony, to descend to the yellow node. Go forward to the second yellow disk to move to the Laboratory. Go inside, then back screen out to the sky bridge. Follow around to the back of the balcony. Use the red disk there to move to the Atrium area. Go down the left stairs and go up the right stairs. Use the blue disk to arrive back at The Forge. Inside, witness another discussion of Zak's condition and his desire to be a human being again.