Surface model of human aquaporin 4 based on the crystal structure 3gd8 from the following paper:

Crystal structure of human aquaporin 4 at 1.8 A and its mechanism of conductance.

Ho, J.D., Yeh, R., Sandstrom, A., Chorny, I., Harries, W.E., Robbins, R.A., Miercke, L.J., Stroud, R.M.
(2009) Proc Natl Acad Sci U S A 106: 7437-7442

If you print 4 of these they will stick together without any adhesive to form the tetramer.