3D printing’s always been stuck with a pesky size limit—your average printer’s cramped build area forces makers to slice big designs into awkward chunks, gluing them together like a clumsy puzzle. It’s a pain, and the results often scream compromise. But what if you could churn out massive creations in one shot without needing a warehouse-sized machine? Makers Ivan Miranda and Jón Schone spotted a treadmill—yep, that gym staple—and turned it into a mind-bending 3D printer that spits out giants, like a two-meter girder or even a full-blown kayak.
