What is hot glue? Where to buy hot glue gun and how to use.

This thing is just irreplacable! I don't know how I used to live without it.
It's reaaaly cheap as well on ebay: Heating Hot Melt 20W Glue Gun Crafts Album Repair with Glue Sticks 28mm 7mm
You can probably find a dispenser/gun for a couple of dollars. I ordered a gun and 30 sticks for just 13.25$. It's not like you're gonna be using a stick per day, 30 stick will probably cover you for a year or more.

What is it for?

Replacing battereis with an AC adapter for a LED UV pocket flashlight

I had an idea of making a 9-LED UV/Blacklight flashlight, and to use it as a small UV-lamp. And I also wanted it to work constantly, without having to replace batteries or recharge li-ion accumulators.

Here is an example of what you can get on Ebay for just 2$: 9 LED Ultra Violet UV Blacklight MINI Portable Flashlight Torch Light Lamp CSI
You could buy a big and expensive UV-lamp, but it's not a good option because of
a) power consumtion;
b) amount of UV they produce.

Selfmade (modified) variable voltage AC using step down converter

Let's suppose that you need to plug something in that requires less voltage than any of your spare ACs give out. I had to make a thingy work that needed 3.5-4V max, but I only had 5,9 and 12 volts ACs at my disposal. What do you do in that case? Well of course you could order voltage-variable AC on ebay, that comes with a lot of plugs too! But then you'd have to wait for shipping and pay somewhat 10$, but you already have a lot of ACs, why not upgrade them? Besides, the majority of variable ACs are not really adjustable, they have 3-5-9-12 switch, and that's it. So you can't really use thouse if you need exactly 4.2V output.

The things you'll need: