Sinter gives hardware teams injection-molded plastic parts without a machined steel tool as the starting point. Its site marks the usual route across twelve weeks, from supplier search through an offshore tool build, shipping, and revisions, before the first molded part. Sinter prints core and cavity inserts in photopolymer resin, shoots them on standard presses, and bills by the part with no separate mold charge, including on very small runs. It also quotes FDM prototypes from an uploaded STEP or STL file, with price and ship date in minutes. CEO Oliver Johnson and COO Justin Kwon founded the company in 2025. It is a two-person team in Y Combinator's Fall 2026 batch. Johnson previously ran a 3D print farm, and Kwon previously worked on mechatronics at Shinkei Systems. The two met as teenagers building custom mechanical keyswitches. Sinter says it prints tools on a Formlabs Form 4BL with formulated photopolymer resins and can build and shoot that tooling in 48 hours. The company says teams use those shots to check mold design in end-use resins, including materials that cannot be printed as finished parts. It says the work runs in-house in San Francisco, while Y Combinator lists the company in El Segundo.