Hey, is it actually possible to build a junk tardis and have it actually fly or not? If it's not could you add it as it'd make it cooler to be able to just build a tardis w/o an exterior.
Anything is possible. If I can make a working TARDIS (bar dimension hoping) in vanilla, then its probably possible to get a block built junk TARDIS to work. To do it, I'd imagine john would need to set up a Archimedes ships type system though, which would probably be difficult to do.
That sounds like a nice suggestion, as it will allow for player customization.
It might be better to post it in the Suggestions section so more people can notice this. :D