Mini Bungee

An extremely simple hook used to create a mini bungee. Knot your elastic on one side and use it to wrap around anything. Unlike a regular bungee cord, the mini bungee connects to itself - this makes it great for wrapping around items like bags, sleeping bags, and other objects where the size or shape make standard bungees difficult to use.

Printing (unless stated otherwise, use your preferred printing settings):

• Perimeters - I went up to 5 perimeters for rigidity.
• Infill - I used gyroid 30%, though you can probably drop to 20%. Infill helps with strength, but the perimeters are doing much of the work.
• Orientation - Keep it as provided in the STL. The holes are shaped to not need supports and print well, while the layers will be perpendicular to the stresses placed on the hook, maximizing strength.
• Filament - PLA and PETG are the two I have used, with no noticeable difference. I suspect that PLA would fail first, but the thickness of the elastic cord probably means that the cord would fail before the tension snapped a hook.

Construction:

• I used 3mm (1/8") elastic cord (specifically https://www.amazon.com/gp/product/B08JV4HZQ9/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1)
• Cut the cord to your preferred length (remembering to double the length if you have a specific use in mind, since the cord will be doubling back on itself).
• Insert one end of the cord into a hole below the open face of the hook and tie a stopper knot on the other side. I have tried the figure eight knot, stevedore knot, and Ashley stopper knot and found the figure eight to be the best for use in this elastic cord. You should experiment with your cord to ensure you pick the most secure knot.
• Take the other end of the cord and thread from the same side as the first, tying off the knot on the same side as the first stopper knot. You should now have a pair of stopper knots on the outside and a loop on the inside (where “inside” means the open face of the hook).
• Trim your elastic cord, if desired, and seal using a lighter or other heat source. Be careful! You can start a fire and/or burn yourself at this stage. If in doubt, superglue can be used to seal the ends as well.
  • NOTE: Heat shrink tubing is another option here. Cut the tubing to length and shrink around the cut end.
• Test your new mini bungee!

Cautions:

I am including this section for clarity on some key points of safety.

• The mini bungee is NOT for securing loads on a vehicle beyond lightweight items in (e.g.) a bike basket or similar. The hook has not been tested under the kind of stress that a moving vehicle and/or heavy loads would apply - please do not take the risk.
• Long-term testing has not been carried out, so I do not have any idea if the hooks will degrade over time when kept under continuous stress. I doubt that anything will happen, but I cannot be certain. As with the previous bullet, do not use the mini bungee anywhere a failure could cause harm.
• Upscaling has not been tested. I do not know how it would work with different elastic diameters. I don't think anyone should be dissuaded from trying, I just have no data to tell you if it will work or not.
• Finally, working with any elastic carries risks, limited as they are. Elastic stores and releases energy; if the mini bungee you print fails, that energy is going to be turned into movement and possible projectiles. This is unlikely to do much damage unless it hits you in the eye(s). Just remember that you are dealing with a home-printed solution and that the failure state for your prints may be unlike my own.

Hope you all enjoy!