Pocket LED Flashlights

Pocket LED Flashlights

These are great little flashlights for short little tasks where you only need a little bit of light for a few seconds. The banana in the first image is there for scale. Keen observers will notice that it's not a real banana and is actually a 5x3 LEGO block. The flashlight is about the same width and length as the block but only half the height, for the CR2025 version.

I suppose typical usage might be to attach it to a keyring and use it to find a keyhole in the dark, but I have several of these placed around the house that I've been using for a few years and have found them to be very useful for other tasks. I have one on my night table to find my glass of water in the dark. I have one on a table that's handy for checking if the front door is locked. I have one on my computer desk to see the keyboard so that I can unlock the computer. Fumble in the dark, turn on a house light, or use one of these bad boys. 

This is a remixed model with a reinforced button and an alternate bottom piece. There are two versions of the bottom piece: one for a CR2025 cell and one for a CR2032 cell.

Remix Details

The original source that I remixed this from is a great design, but after several hundred presses of the button I've had two of them break and a couple more that are close to breaking. So I remixed the model with a reinforced button. I've tested the stength just by feel and it seems to be much stronger.

WARNING: MATH AHEAD. The original lasted three years before the button broke. A 160 mAh CR2025 battery should power the 20 mA LED for 8 hours of continuous use, and a 225 mAh CR2032 should power it for over 11 hours. But it's typically used for less than 5 seconds each time, so that's over 5,760 uses for the CR2025! I estimate that the original broke after about 600 uses, so hopefully my reinforced variants are at least 10 times stronger and I'll let you know in 30 years when the batteries die that they worked.
 

Assembly

You will need the following additional materials:
  1 x 5mm 3V 20mA LED light
  https://www.amazon.ca/gp/product/B01AUI4VQU/

and
  1 x CR2025 3V coin cell
  https://www.amazon.ca/gp/product/B0B4BW3ZG6/
or
  1 x CR2032 3V coin cell
  https://www.amazon.ca/CR2032-Volt-Lithium-Coin-Battery/dp/B08FD7RHT4/

The shorter wire on the LED goes on the negative (bottom) side of the cell. I applied a small spot of GOOP® glue on each of the 4 posts of the bottom piece before assembling the parts together and clamping it with a couple of binder clips. The GOOP glue keeps the parts together, but still allows them to be pried apart in case you need to replace the battery or the top piece if the button breaks. 

Note that the middle piece is non-symmetrical from top to bottom, but it's not really that important since the difference is so slight. The STL model is oriented upside down for printing.