This is a bookmark sized flashlight with paths etched for copper tape. The CR2032 battery pack folds around the back.
Files are on thingiverse: https://www.thingiverse.com/thing:4798489
- Copper tape with conductive adhesive backing. https://www.adafruit.com/product/1128
- CR2032 battery holder with on/off switch. https://www.adafruit.com/product/783
- CR2032 lithium batteries. https://www.adafruit.com/product/654
- SMD LEDs https://www.ebay.com/sch/i.html?_nkw=smd+led+0805
- SMD Resistor 390 – 510 ohm https://www.ebay.com/sch/i.html?_nkw=510+ohm+resistor+0805
Download the files from thingiverse. Start with the .scad file in OpenScad. Modify the print height variable to match your printer. The battery clip is attached by a hinge that must be a single layer high.
Render and save the stl. The bookmark and battery glue tabs is about 9 inches long, I rotated 45 degrees to make it fit on my 3d printer bed.
I also set the bottom fill pattern to Octogram Spiral, in an attempt to make the hinge stronger. Side effect is you get a really neat star pattern too.
I cut the copper tape in half to get the trace width I wanted. When soldering the copper tape, lay the tape as one solid piece. Then cut on the notches to open up a gap of approx 1 – 1.5mm. Goal is that the copper track overlaps each LED by approx 1mm.
Solder it all together, be fast on the copper tape. More than a second of heating is enough to deform the plastic. If you make a mistake, wait for it to completely cool before trying again. It might take you a few prints to get one that is pretty looking.
Test with a spare resistor and battery. You remembered to install the LEDs all facing the same way, right?
Lastly, super glue the battery clip onto the tabs and clamp.
You have a really neat, super thin flashlight. Print out a sticker to hide/protect the copper and act as an LED diffuser.