In the archives of the Germanic Museum in Nuremberg there is a Renaissance wood engraving that is thought to be the earliest paper model template ever created. The engraving was produced around 1529 by Georg Hartmann (1489 - 1564), a mathematician and designer of scientific instruments. When the template in the engraving is assembled it becomes a crucifix that also ingeniously functions as a sundial (the shadow in the photo on the right is at 11 o'clock).
There are numerous images on the crucifix. On the front is an engraving of the crucifixion of Christ that is very similar to a 1489 woodcut print by artist Albert Durer (1471 - 1528). Some sources suggest that Hartmann was a pupil of Durer's, which might explain the similarity. On the back of the crucifix is a bronze serpent on a cross and an image of Moses in reference to a miracle performed by Moses in Numbers 21:8-9. In the Gospel of John, Jesus Christ refers to Moses' miracle as a symbolic foreshadowing of his own crucifixion (John 3:14-15) thus explaining why Hartmann included the bronze serpent on the crucifix.
As far as I know there are no free papercraft templates of the crucifix, but reproductions may be purchased from several different European sources. One such source is here. Also on the same web page is a photo of the cross unfolded if you are curious.