A separate task is going to be designing the battery holder. For now I'm just using an off-the-shelf battery box, with a switch on it, and it's enough for testing, but eventually a separate special design will probably be necessary.

There are two main problems to solve here:

1. Since the battery holder will be worn on the back of your neck, it will be in contact with a rather sensitive part of your body — I will need to make sure it's safe for your skin.
2. Since it's relatively large and heavy, an ergonomic shape will be necessary.