Hi
It's always silly if your mobile or tablet doesn't work, so I built me a not too big Powerbank with a lot space to upgrade it

Step 1: Parts

- a box for everything
- a car 12v to 5v converter
- a mini cooler
- 2 switches
- fly screen

- 9v battery with battery holder
-or/and rechargeable battery with holder with max. 12v and min. 5,5v

- hot glue

Step 2: Holes

Now you have to decide were the components should be, cut the hole and stick them there

The holes you need are:

1 for the Usb
2 for the switches
1 for the cooler
1 to let the hot air out

Step 3: After That

Now stick all the components into the holes and cover the cooler and the hole for the air to come out

Like on the picture

Step 4: Cables

Now you have to cable up the cables so, that you can use one switch to switch the cooler on and off and the other one to switch the usb outlet on and off