My son has a rare genetic disorder (nyctalopia) in which the rods in his eyes don't work and so he can't see anything in dim light. I've seen him very confused and scared in environments where I can see perfectly well.

I want to make a flashlight for him that he can wear on his wrist (or around his neck) at all times. Other flashlights aren't helpful because he has to remember to carry them around, which he won't do (he is little).

I've looked online and not found anything suitable. All the wrist lights I found are just too big. They have compasses attached, etc.

The main guidance I'm looking for is safety (a reasonably strong battery that has the right form factor and is still safe to have close to his body), and after that the best lights to use. I think just a headstart on what battery to hook up to what light would be a massive help.

How to do water resistance would be nice but it's not essential =)

  • \$\begingroup\$ I’d imagine you’ll need to start by finding out what level of illumination he needs, and whether white or coloured light is better. That will give an indication of the power requirements. \$\endgroup\$
    – Frog
    Sep 21, 2023 at 3:08
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    \$\begingroup\$ For small watches is hard to implement a parabolic reflector so better find a Led with narrow illuminating angle (about 60 deg). Regarding the power of Led the 1W is the minimum, 3W is better but it will drain the small battery too fast. For battery find some small pack (the silver sack whitch has not too weighty enclosure) best fits to watch case. \$\endgroup\$ Sep 21, 2023 at 4:17
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    \$\begingroup\$ Keychain lights are smaller than wrist- and head- lamps. Cap lights are also smaller than headlamps. \$\endgroup\$
    – david
    Sep 21, 2023 at 5:02
  • \$\begingroup\$ Have you looked at head lamps (search Amason for "led headlights for head")? Something that always points in the right direction will be more useful. Buy 2, one for you, make it a game so he won't feel weird wearing it. \$\endgroup\$
    – Mattman944
    Sep 21, 2023 at 8:37


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