Simple extendable print-in-place chain. It was tested with 0.4 mm nozzle, 0.2 mm layer height, no supports. The main file contains STL with 16 connected links (length is about 200 mm). Size of one link is about 21 x 25 mm. There is also a SCAD file to customize a layout.

Methods of connecting to make a longer chain:

1. Print chain-link-cut.STL, enlarge the slit, and insert chains ends there. Glue is optional.
2. Start printing chain-link.STL on its side. At ⅔ of printing, pause, and insert chains ends (see a photo).

Both methods work, but the first one is less noticeable and more sturdier.