If you have read my other business card instructables, you will know what this is all about - make a business card that is useful, or that people really don't want to throw away, and you have a successful piece of advertising. This is a variation on my previous flashlight card, but made to look a bit more flash, and to be easier to construct - no PCB needed for this one - just some self-adhesive copper tape. The finished design costs less than a dollar to make, and they are simple enough to make up a small batch of these in an hour or two.
Step 1: What You Need
- One CR2032 battery (I got them for about 16 cents on ebay when I bought 100)
- Two blank PVC ID cards (Again, I got these for about 16 cents - find a specialised ID card printing store on the web near you - I used www.digitalid.co.uk)
- One 3mm High-intensity white LED (Ebay again! I got 100 for about $16, so 16 cents each again!)
- Some double-sided foam adhesive tape (I got mine from an office supply store for a couple of dollars - you just need tape that is thicker than the battery you are using - mine was 4.5mm thick)
- Some self-adhesive copper tape (Ebay! Mine cost a few dollars for a long roll of 1 inch thick tape, and I cut it into thinner strips, but you could also buy the thinner version)
You will also need a soldering iron (plus solder), a cutting knife, some spray adhesive, and a way of printing the front of your card - you can use a colour laser or inkjet. I printed on paper and laminated it, but have had success before with printing in reverse on OHP transparency film which can look good as well.
Cut a couple of strips of copper tape about 1/4 inch wide and 2 1/2 inches long. Solder one end of the LED to one of the copper strips, starting about half way down the lead of the LED. Make the connection so that the soldering joint is close to the edge of the copper strip, and dont use too much heat, or the selfadhesive backing paper peels off. Then turn the LED over, and do the same on the other side.
Step 3: Attaching to the Card
One of the leads of the LED will be longer than the other - this will connect to the positive of the battery. Peel off the backing of the copper strip attached to this one, and apply to the middle of one of the blank ID cards. Try and get it so that the LED is poking out just a little from the edge of the card.
Step 4: Attaching the Foam Tape
Apply some self adhesive foam tape around the perimeter of the card, and also around the battery to stop it moving. Make sure that the unattached copper strip is free to go above the battery - it does not need to be stuck to anything.
Step 5: Attaching the Overlay
Design the layout of your card on the computer, and print out - I just printed on plain paper and then laminated it. You might will want the image to be a little bigger than the card (called a "bleed"), so that you can cut it exactly to size later, and not have a white boarder around it. Spray some adhesive on the back of the printout, and attach it to the unused ID card. Then turn the card over, and cut neatly around the outside of the card. Finally, attach this ID card to the front of the electronic assembly.
Step 6: Changes
If you are making a few of these, you can ditch the double sided tape and use foam sheeting, attached with self adhesive spray. By using one of the blank cards as a template and cutting out around the outside, you can get a neater edge on the finished design. You can then just cut holes for the battery, and LED, making sure there is a vertical cut halfway down the card for the top copper strip to poke through. You might also want to fix the LED a bit more securely so that it doesn't get knocked around in use. A blob of 5 minute epoxy does this job well, and is transparent as well.
If I produced these on mass, I would probably change a couple of things. Firstly I would change the CR2032 cell to a CR2016 as this is thinner, and also design a custom self-adhesive foam cut-out for the LED and battery to replace the double sided tape. Getting the cards printed professionally would then allow the cards to be assembled in seconds each, rather than minutes. If anyone is interested in getting commercial versions of this card or another design produced for corporate use in quantity, I can be contacted at firstname.lastname@example.org. (Or if you want to give your kids a really great time next summer, check out the Tech Camp!)