Update: 21/04/2016. Added single screw and banjo STL files.

A full size, 3D printable replica of the Legris banjo and screw used on the Ghostbusters' proton pack thrower.

The part pictured was printed in ABS, then treated in acetone vapour to smooth the sides.

It was then painted to give a brass like effect.
I've detailed how I did this at:
http://funwithelectrons.blogspot.co.uk/2015/01/making-parts-look-right.html