Since getting into audio books a few years ago I've accumulated quite a collection. Now it's time to find them a permanent storage that I can also take with me when I travel.

After looking around for an already made solution, both diy and buy options were horrible.

So here we are!

My solution is designed around the standard paper folder with rings.

Supplies

For materials I used

thin folder with rings 2.95€
zipper (50cm, bigger teeth) 0.48€
thick string(non-elastic) 1.60€ (for the whole roll)
soldering paste 27.21€ (35ml)
self-designed circuit boards 5.15€ (delivery 18.04€)
micro sd card holders 30.80€ (for 20 peices)

and tools are:

electric stove(not inductive)
drill
drill bit 1mm
drill bit 3mm
ruler(I have a fancy one, but a regular would do just fine)
tweezers
scissors
sewing needle

If you were to repeat my project, it would cost about 60€ (90€ if you don't have soldering paste and the string) and an evening of your time.

Step 1: Circuit Board Design

I began with the circuit board. I'd love to attach my Gerber file, but for some reason it doesn't allow me to.

Learning Easy EDA was quite simple after Great Scott's video https://www.youtube.com/watch?v=35YuILUlfGs

The card holders are 2mm away from the edge. This is done on purpose, otherwise they would stick out too much. But this way you can still push the cards in and there is almost no chance to accidentally push the card while it's stored.

Through holes are 80mm apart on center and 3mm wide.

The board is symmetrical, so it can be flipped without re-designing the folder.

After designing I ordered the circuit boards from a chinese vendor as well as the Micro SD card slots and soldering paste.

Step 2: Circuit Board Soldering

After about a week, after receiving the circuit components, it was time to solder them together.

I applied the solder paste to the contacts by hand.

Placed the components using tweezers and alligned them.

Turned on my electic plate to the lowest setting, placed the boards one by one and waited for all the solder to melt.

Removed all the boards and allowed to cool off.

Step 3: Cutting the Folder

The plastic is qute soft, so cutting the folder was done with scissors.

I simply hook the boards, measured, marked and cut across. Then repeated with the sides.

Step 4: Drilling Holes in the Folder

To attach the zipper I had to drill holes...a lot of holes.

I marked and punched the marked spots for easyer drilling.

For the holes I used 1mm drill bit and 3mm to clean up the blowout.

I'm sure one row would be plenty, but aesthetically I like the two rows a lot more :)

Holes are 2mm and 5mm away from the edge and 5mm apart (except the corners)

Step 5: Attaching the Zipper

This was the longest step.

Beginning with a straight line seemed best to me, so I alligned the edge of the zipper to the metal part, aligned the next edge and started "sewing" away from the spine.

It was at this point that I realized that I forgot to drill holes on the spine. I also cut the zipper a bit to ease access in tight spots.

The order of operation: