Parametric, Print-in-place Serpentine Chain

The SCAD code can generate a chain of arbitrary length (limited by your print area). 

Variables:
ow - width of print area (x direction)
ol - length of print area (y direction)
w - width (and height) of a single link
l - length of a single link (from pin to hole)
addClasp - add a clasp to the last link

Example STL files are included for 4x8mm, 6x12mm and 8x16mm links, each about 300mm long. There's also a full-print-area (200x200mm print bed) chain using 6x12mm, for a total length of about 1400mm.

Note: The “clasp” is just a modified link that's open-ended with a small groove to keep the mating link in place.

You can technically print this with PLA, but it'll tend to be a bit brittle. PETG is probably better. 

You can adjust the length of the chain using the overall print area. The SCAD code will calculate the total length. If you need to alter the total length a bit, you can always add or remove a few links in the slicer app.

Added Bonus: If you use the loop() module instead of the snake() module, you can generate a circular chain of a given length, either closed or with a clasp.