Blood knot tool

I printed the parts in PETG, but PLA should probably work, too.

You'll need to bend some heavy gauge wires to make the pincer arms. I used Monkey Hook Picture Hanger Hooks from Home Depot.
You also need either either latex tubing or silicone tape to wrap around the top arms.

The picture shows a printed tool next to a purchased Dennison Blood Knot Tool. I have not added the silicone tape to secure the clips yet on the one I printed.

Here is a YouTube video (not mine) that shows how to use the tool.

https://www.youtube.com/watch?v=K9RMpiAcsy0