This is a simple, printable paracord tensioner based on a similar design that's usually sold and made from anodized aluminum. I haven't tested yet to see how much load it can support, but should be plenty strong for camping applications such as tying down tent stakes, clothes lines and more.

You can watch this video (not by me) to learn how to use it: https://www.youtube.com/watch?v=w34OC063BQA&t=220s

Print instructions

Print with multiple shells to increase the strength of the part. I have printed this with 3 shells in PLA and am able to get some pretty significant tension without deforming the part.