a friend and i are planning to make a replica of this bust what

>>988348
Make a mold

Carve it out of concrete

>>988348
if you are smart enough, use some cad software to make many layers of contour lines of the thing, then cut up the layers with cardboard or sheets of any material, then stack them up

>>988348
>3d print a mould.
>fill with plaster.

>>988371
Probably be better off 3D printing the bust itself, then manually smoothing and refining the print, then using the smoothed version to make the mold. Otherwise your mold is going to have layer lines in it.

>>988356
this can be done with Autodesk's 123D Make, and is a good solution if you don't mind the layer thickness. http://www.123dapp.com/make

>>988371
works but you will need to hand-finish the mold (or positive) quite a bit, else it will perpetually stick and tear

I'm surprised no one has just mentioned:
3D print it from sandstone in one go. Leave the inside hollow for cheapness.