Simple Wireless Key Fob Faraday Cage

Construction is simple, and requires only regular aluminum foil (not heavy duty). No glue, or anything else. Everything press fits together.

Print:

• 2 x Inner parts
• 2 x Mid parts
• 1 x Outer Bottom
• 1 x Outer Top

Optionally, print the template parts for very easy aluminum foil cutting or print a template PDF page. Note that if the side template part is not printed the side strip of aluminum is a rectangle that needs to be measured. The dimensions are written in the PDFs.

For each half of the box, use one inner part, one mid part, and one of the outer parts. You will also need aluminum foil cut to the asterisk looking shape (the main shape), and two aluminum side strips.

Construction begins by wrapping the mid part in foil. Place the mid part, facing up, on the asterisk foil, and wrap the side foil strips around the entire outer circumference of the mid part. There should be some overlap between the side strips. Then fold the asterisk petals up and over side strips, and the edges of the mid part walls. Make sure everything is smooth.

Place the foil wrapped mid part, facing up, into the outer part. It should slide in snugly. After placing all the way, refold and smooth any excess aluminum foil pushed up by the press fit.

Take the inner part (potentially upside down to the print orientation, if your parts have significant elephant's foot) and push it, hard, all the way into the slot in the mid part. Ensure that the foil is nice and smooth while pressing in. 

It may take some effort to push the parts into their positions but it is critically important to ensure they are all pressed in all the way, and snugly in place. Otherwise, the aluminum contact patches between the two box halves may not make contact and the faraday cage will not work (see the aluminum contact patches in the photo).

Test that the faraday cage is functional by placing your wireless key fob inside, closing the box, and attempting to open the car with the box right up against your car.