A paddle grip hand locator, used for sprint/marathon or surfski (wing)paddles. It ensures consistent hand placement by creating a tactile oval shape on your paddle shaft. With the knob you've got the correct hand placement without needing to look.
Avoid using PLA, this will soften when your paddle is baking in the sun on the beach. I've printed it in PETG. My best results are printed as shown (with the concave side down), with supports underneath.
I like to have the knob between my index and middle finger when I'm paddling. Once you find your preferred hand position you can attach it to the paddle shaft with some electrical tape on both sides, and finish with an anti-slip heatshrink or your preferred wrap.
The heatshrink tube is easily found on Aliexpress, I think it is used for fishing poles. For my (Braca) paddle I use the 35mm heatshrink. In my experience the hot water method is easiest to shrink the heatshrink.
The author marked this model as their own original creation.