If you don't own a 3d printer..

You can find 3d print services online in Ηubs or in Shapeways, you send your design and they deliver your part.

Or you can find in 3d printers in your local hackerspaces and makerspaces. 

A makerspace is a collaborative work space inside a school, library or separate public/private facility for making, learning, exploring and sharing that uses high tech to no tech tools.  These spaces are open to kids, adults, and entrepreneurs and have a variety of maker equipment including 3D printers, laser cutters, cnc machines, soldering irons and even sewing machines.  A makerspace however doesn’t need to include all of these machines or even any of them to be considered a makerspace.

https://www.hackerspace.gr/ http://athensmakerspace.gr/  https://www.ludd.gr/