They did this by putting pieces of silicon or one of a number of other solid materials inside a shoe-box-sized cavity and zapping the material with microwaves from a metal tip.
The consortium tested the practicalities of using a printer on the Moon by setting up a D-shape 3D printer, which are used to print very large house-sized structures, in a vacuum chamber with simulated lunar material.
Dr Murray stressed there was no direct evidence these stars did have Earth-sized planets in orbit about them, but modelling had shown that if sufficient terrestrial material existed in a system it would eventually clump together into bodies as big as the Earth.
According to his company's website, Mr Dini's industrial sized 3D printer uses sand and a special binding agent to create a "marble like material" stronger than cement.
Set the company's iPhone-sized speaker on a desk, coffee table or even a surfboard and it transfers sound waves into that material -- creating an on-the-fly subwoofer.