A spiny dendrite in the neocortex of a mouse, from "Saturated Reconstruction of a Volume of Neocortex" by Kasthuri et al. http://dx.doi.org/10.1016/j.cell.2015.06.054

Three versions of this model are available, the original, a remeshed version which has been simplified, and an extruded version where all the components have been thickened.  The remeshed and extruded versions will be easier to print, but do not accurately preserve the proprtions of the dendrite morphology.