This is an STL file for you to print on a 3D printer.
This fin has been designed as two parts: the top fin, and the base. There are (6) 10mm x 2mm marked for magnets to attach the fin to the base. There are a few more areas for smaller magnets should you feel the need for additional support. I used neodymium ring magnets that are 9.5mm x 1.5mm that I bought from Home Depot. You are also able to glue the fin to the base if you don’t need it to be detachable.
The support pins in the base will fit very snugly into the top. You can use a dremel to sand these pins down for a better fit, but not so much that it will be loose. If you sand too much, you can build up the pin again with bondo or another type of strong material.
This fin is designed LED Ready!
The front area is open for you to place an LED, and there’s space in the base for a dual AAA battery holder. I’ve designed a space for a small switch in the back of the fin that can be used to power the light on and off. If you aren’t using LEDs, you can plug these open areas with bondo or epoxy. One suggestion for the front open area is to place a clear or red film on the inside. I made a box with red film that fit snugly inside the opening. Feel free to get creative!
Tips for gluing the base to your head:
Ideally, the wearer would be able to remove the fin when needed without disrupting the base. One method for adhering the base to your head is to cut long thin strips of floor mat eva foam (or even thin, flexible mousepad material which will resist tearing as you take the fin on and off) and superglue them into the edges of the fin base. The base can be adhered to your head with a medical grade adhesive such as Prosaid. I do not recommend using spirit gum, as it doesn’t have the strength to hold the fin assembly in place.
You can use a material like latex or cabopatch to create a layer that will hide the seam between your head and the base.