The 115-foot-tall (35-meter) Terran 1 rocket, 85% of which was fabricated from a 3D-printer, was set to lift off from a U.S. Space Force Base launch pad in Cape Canaveral, Florida, at 1 p.m. Eastern time (1800 GMT) on Wednesday.

“The launch that we’re preparing for is an opportunity to demonstrate a whole bunch of things all at once,” said Josh Brost, Relativity’s senior vice president of revenue. He called the Terran 1 “by far the largest 3D-printed structure that’s ever been assembled.”

The 3D-printing process, widely used in various industries, involves machines that autonomously “print” sequential layers of soft, liquid or powdered materials that are quickly hardened or fused to form solid, three-dimensional objects. Designs of the objects are scanned from digital blueprints.

Relativity, one of a handful of U.S. rocket startups competing to sate the growing demand for cheap launch services, has bet on the cost savings it expects to achieve using giant, robotic 3D-printers to simplify its rocket production lines. Most of its rivals have focused on lowering costs by building rockets designed to be reuseable, such as the Falcon 9 boosters produced by Elon Musk’s SpaceX.

The use of 3D-printers, Brost said, allows Relativity to hasten much of its manufacturing processes and more easily make changes to improve the rocket’s design if needed after it flies, eliminating the need for a complex supply chain that would otherwise slow down rocket enhancements.

While the expendable Terran 1 is built to carry 2,755 pounds (1,250 kg) of satellites to low-Earth orbit, waning demand for that class of launch vehicle has led Relativity to develop a larger, 3D-printed reusable rocket - the Terran R - that it expects to fly in 2024.

Currently driving demand are the so-called mega-constellation plans by companies such as SpaceX, OneWeb and Jeff Bezos’ Amazon to deploy tens of thousands of internet-beaming satellites to low-Earth orbit in the next few years.

SpaceX flies its own heavy-lift rockets to get its Starlink network into orbit, while Amazon and OneWeb plan to use similar large rockets from various launch companies for their own satellites. OneWeb will launch its next-generation satellites on Relativity’s Terran R, the companies announced last year.

Relativity, headquartered in Long Beach, California, has roughly $1.65 billion worth of launch contracts secured for both its rockets, with the bulk of that revenue attributable to the larger Terran R.

While market demand for rockets like Terran 1 has weakened, Brost said the rocket’s upcoming flights will inform how Terran R is engineered.

Asked if Relativity is still selling Terran 1 to customers, Brost said the company “continues to talk to people about both vehicles.”