Scientists have a long way to go before they can match the self-building powers of the human body. But now, a new technique for assembling flexible polymers and living cells may get them one step closer. Previously, researchers investigating how tissues and organs function (or don’t) had few options for creating artificial tissues—so-called organs-on-chips—that they could use to avoid experimenting on animals and people. They typically built their tiny organ models one piece at a time from individual gel bricks filled with suspended cells, a time-intensive process that limited what the bricks could be made of and how they could be shaped. Now, scientists say they have solved those problems with microfluidics and electricity. Using electric fields, they can push and pull tiny, particle-filled droplets between two glass plates, assemble them into a larger configuration, and treat the droplets to form adhesive gels. This lets them control the droplets’ movement and manipulate the particles, like cells, suspended within. As a result, they can assemble gels from a wide variety of materials and control the configuration of both the bricks and the cells inside them. Already, the researchers have used the technique to create a heartlike tissue whose cells beat in time, they report today in Science Advances. If the technique can be refined to provide perfect control of cells, it can be used to build precise architectures of living cells, paving the way for artificial tissues, cell-based robots, and more sophisticated organ models.