Print-In-Place with no additional hardware required, making it's easily scalable up or down.

All of the credit for this design should go to the original designer:

https://www.printables.com/model/565344-automatic-rope-tensioner

I've just made a cosmetic remix of the Automatic-Rope-Tensioner (filled in the screw holes, as they're not required).

Both this version and the original can be Printed-In-Place using organic supports.

I sliced it in PrusaSlicer using a 0.25mm layer height; 4 walls; 20% infill; organic supports on build plate only.

I've also tried printing it scaled down to 70% and as you can see, it works quite well (the locking mechanism moves a bit rougher though).  With it scaled down to 70%, it's a very nice size for using with 550 paracord (it's actually way smaller & lighter than a NiteIze).