Nothing easier then that. Order a red and a light blue (cyan) foil in a homeworkers shop. The colors of the foils are perfect when there is hardly any light shinning through if you put them on top of each other. You can order this filters online at www.3d-foto-shop.de
Simply cut a frame out of cardboard and stick the foils in the eye openings. The red foil must be in front of the left eye.