Bookmark Flashlight

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

Part List:

• 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

Printing

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.

Assembly

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.

Finishing Ideas

You have a really neat, super thin flashlight. Print out a sticker to hide/protect the copper and act as an LED diffuser.