Making a Smaller Passive Key Fob

[Moonhowl]

I was pretty excited about this mod, and purchased and programmed a spare key fob for my 2020 Mustang GT. I acquired the .STL files for the top and bottom pieces and had a friend 3D print them for me. Finally, I cracked the spare fob open and removed the PC board and battery. It was very obvious that the board and battery was much too big to fit in the case. It seems that Ford changed the key fob design for the 2018-2020 Mustangs. The new design uses one CR2450 battery. Both battery terminals are attached to the same side of the PC board. The four buttons are surface mounted to the opposite side. Does anybody have a mini case that fits this board?

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[Moonhowl]

I decided to use the bottom half of the case with the battery compartment and cover, and throw away the top half of the case with all the push buttons. I replaced the top half by covering the pc board with 2-part epoxy putty and sanding it to shape. The result is 2/3 the thickness of the factory fob. I plan to add more putty and sand to make it prettier.