When I was much younger I use to play a lot of space games such as Wing Commander and wishing I could build and fly my very own space ships.
I noticed in the last couple years quite a few alpha stage games have popped up that let's you do just that, and it's amazing just what they are capable of.
Here is a list of the newer space ship "sandbox / building / simulation" games that I know of. If I missed one, let me know !
================================ Playable ================================
Build Your Spaceship and Explore the Universe
================================ Unplayable ================================
================================ Dead In The Water ================================
================================ Failed ================================
Infinite Pixels