This drag chain is actually parametric and can be customised via the source or the customiser available on Thingiverse. Two popular sizes are available here.
The chain is designed to be printed assembled. You can choose to print any number of links, and whether to include the chain mounts. The performance of this chain compares admirably to that of commercial chains. https://www.youtube.com/watch?v=TQgd3H_QV24Instructions
Practical limits apply depending on your printer abilities, the design is best printed assembled. Choose as many links as your printbed can fit, remember you can rotate at 45 deg to fit more.
Once printed the chain will be slightly fused depending on your printer quality, you need to work the chain loose. If the chain is fused to solidly and breaks try increase the "Anti Stick" parameter, be sure to take a bit of time to work the links so they are nice and loose, squeezing the pins while doing this helps.
A shell thickness of 1.5 -> 2mm usually gives the best results, the minimum chain size is mostly limited by your printer calibration and quality. Some of these instructions assume you are using the source to customise the chain.