I found a nice scan by Donald Farnsworth here: http://www.123dapp.com/obj-Catch/Athena/2010889 (Carrara marble. Roman copy of Greek herma 49-25 C.E. Height 49 cm. Inv. No.6322. Naples, National Archaeological Museum.)
I edited the file so it is 3D printable. I used MeshMixer to fill holes, sculpt some parts, scale the model and cut a flat base for easier printing.
The author marked this model as their own original creation. Imported from Thingiverse.