What is the most interesting thing you have seen done with a 3D printer or 3D printing technology?i

I guess mostly would be playable/usable items like a Guitar you can print from Thingiverse or the functional Clock.

If you could build your dream 3D printer, what would it include and what would it do? Let your imagination run wild!

I guess a House builder, That would print a house within so many days simple by that printer,
After that i would like a Delta printer as dream or a SLA?