Depending on your budget, there are a lot of options out there.
If you can afford it, you can model your parts in some CAD software then outsource them to be made for you.
3D printing (SLA) is nice for its versatility, if you can model it they can probably print it for you.http://www.forecast-3d.com/
is my 3D printing shop of choice
If plastic isn't good enough you can have your parts machined out of aluminum.
Check out http://www.protolabs.com/
- First Cut. They have some pretty advanced automated CNC milling. Its pretty cheap too, for custom machined parts.
I am not sure if either of those shops ship to Italy, but I wouldn't be surprised if they did.
Just to give you a very rough idea it costs about $80 to have a part the size of your hand 3D printed, and about $125 to have it machined. Keep in mind those are very rough numbers. You can get quotes back from those shops or others pretty fast if you want to pursue one of those routes.
I also like to use plexiglas for the chassis of some of my bots. Design it in CAD, print out a template, stick it onto a sheet of plexi and carefully cut it out with a bandsaw or jigsaw and drill out your holes. Plexiglas glue essentially welds the different parts together, giving your chassis a really clean look if you do it with some care.
Hope this helps, best of luck