I did one that was about 1 & a half feet long, it was an original design.
But at the time my model skills were not all that great, and I built it out of a milk jug and peanutbutter container with bits of other models added on it.
It was cool in the beginning, but the more I looked at it, the more I thought it looked like junnk.
It finally met it's doom in a black hole in the trash can galaxy.
I started a Neb-B frigate one time that was to scale with the Falcon kit that's in the Hoth Rebel Base model kit by AMT/ERTL.... it was around the 5ft. range. I got all of the basic shape down, and then being my usual self figured I would superdetail it so I started to cut back into it to add things to the interior.... bad move. I got frustrated and scrapped it. I still want to build it though, so perhaps soon considering i know of better ways of building it now....