9v batteries are the most commonly used batteries.I use a lot of them.Unfortunately, they don't last very long.
this leaves me with a lot of dead 9 volt batteries.
There are many instructables and guides on how to obtain type AAAA cell from 9v battery or how to create a "pranksters battery" ,a hollowed out ancient 6v battery that changes its polarity after a while.
While going through them, while having a problem of getting a proper enclosure for my circuit in the back of my head, I was able to come up with this idea.
In this tutorial, i'll be using this method to encase a heart rate test circuit that I saw in this instructables-https://www.instructables.com/id/Arduino-Heart-Rat...
(a special thanks to usear)
The only alterations I made to it is, use a leonardo pro micro instead of nano arduino to make it fit inside the box.
Step 1: Take a Battery, Open It's Crimp Seam, Carefully and Hollow It Out
I used a knife so blunt that it won't cut paper but can cut copper. it is very narrow allowing me to pry open things with small gaps. carefully start opening the seam from its ends, making your way through it.
pull the internals out carefully.I advise using gloves (despite me not using them) because it could be nasty inside sometimes.
Step 2: Cut Slots and Drill Holes
Mark slots and drill holes according to your requirements.I needed only slots ,so I used dremel to cut them open
Step 3: Bend Sharp Edges of the Slots.
I started with a file, applying exccessive pressure until the edges gets folded inwards.Then I use a pliers to fold them further, until they are flat.
Step 4: Close the Seam
Insert the back plate back in (so that the shape remains rectangular and doesn't warp) and use a pliers to seal the seam back again.
Step 5: (optional) Paint It
At first,I tried using spray paint, but failed because the pressure inside the can was very low, and thus the paint didn't aerosol properly.so i let it dry and scrape it off
then I tried oil paint.It didn't look good so it scraped it off too.
then I used dried up nail polish and gave it a matty look.
Choose your paint wisely.
Step 6: Insulate Your Boards and Insert Them Into the Box
Insulate your boards using scotch tape,while at it Insulate some of the internal surfaces on the box too.
Why scotch tape? it melts when in contact with hot glue thus it doesn't interfere with it's ability to stick too much.
hot glue your boards into position.
Step 7: Seal It's Ends
use hot glue, pour hot glue in such a way that it stick to the walls of the box but not too much to your boards and components unless you want to use it to hold them in place in this manner.
fill it up so much that it overflows
use a tic tac box to give it flat edges by allowing the glue to flow onto it while its hot.
stick the tictac box onto it and move it around to remove any air bubbles. BE CAREFUL not to burn yourself while at it.
wait for glue to dry, then pull the tic tac box off.
If the surface is uneven or it has cracks, widen those cracks and refill them with hot glue and use tictac box to flatten them.
Step 8: (optional) Drop Test It and Test Whether It Works or Not
clean the excess glue and then give it a stress test. drop it from a height of your choice and power it on to see if it can withstand heavy use or not.
This one passed