Along with adding the ability to move and drag already placed structures, I think it would be an improvement if, when you're trying to make a structure the maximum length, you could just drag it out and it will build to the maximum length rather than having to finagle your mouse pointer to the exact point before it gets too long and turns red.
Totally agree with this!!! - whyzkatt Jun. 10, 2009
It would be much better if you could manipulate the pieces lengths and angles instead of having to delete and replace them.