STLBox is a free online library of 3D-printable models, offering 57 original, parameterized parts in STL format under the CC0 1.0 public-domain license. Users can print, adapt, and remix the designs without attribution or licensing concerns. The catalog is in open beta and is organized into six collections: fasteners, mechanical parts, brackets and holders, home and décor, desktop accessories, and printer calibration and testing models.

The selection includes bolts, nuts, washers, gears, pulleys, clips, organizers, vases, and test pieces for settings such as tolerances, overhangs, bridges, and retraction. STLBox states that its meshes are watertight and checked for holes, helping users print them without manual repair. Many designs are intended to print without supports; some home and décor pieces are made for vase-mode printing.

Models are available through direct, permanent download links, with collection archives and PNG previews also provided via the stlbox.ru content delivery network. Users can contact STLBox to report printing issues or suggest new parts.