3-D printers can produce gun parts, aircraft wings, food and a lot more, but this new 3-D printed product may be the craziest thing yet: human embryonic stem cells.

Using stem cells as the “ink” in a 3-D printer, researchers in Scotland hope to eventually build 3-D printed organs and tissues. A team at Heriot-Watt University used a specially designed valve-based technique to deposit whole, live cells onto a surface in a specific pattern.

The cells were floating in a “bio-ink,” to use the terminology of the researchers who developed this technique. They were able to squeeze out tiny droplets, containing five cells or fewer per droplet, in a variety of shapes and sizes.