"Inventing" 2d glasses is pretty simple if anyone wants to do it. The two pictures being projected to present 3D are polarized differently so each eye sees the image projected for that eye.
To make both eyes see the same image (2D), get two pairs of 3D glasses. Move the right lens from the "donor" pair to the left lens of the "target" pair. Bonus: move the left lens from the "target" pair to the right lens of the "donor" pair for a second pair of 2D glasses.
