It strikes me that LEGO blocks make can be useful visualization aids for hard surface designs, particularly if there are moving elements or concerns as to what the concept with look like from all angles.
3D modeling software is nice, but you don’t absolutely need it. Also: SPACESHIP!
Okay okay something happy. Um. OH. TenToo/Rose have a son, who comes home one day and tells them he's gay, and the Doctor is - well, the Doctor XD