Skull symbolism is the attachment of symbolic meaning to the human skull. The most common symbolic use of the skull is as a representation of death and mortality This 3d model were sculpted especially for 3d printing,I have tried to avoid support as much as possible , but you are going to need to use support at least in the helmet overhanging visor.I would recommend to use cura tree support for it ,

The 3d printed piece in the images were print with: PLA,0,12 mm Layer high and tree support.

Have fun !!!