This is how I make the charcoal I use in my drawings.

There are lots of tutorials on the web. But they didn't explain what kind of woods to use or details such as thickness and cooking times. So I figured it out for myself...

• You will need sticks of wood between 1 and 2 cm in diameter.
• The wood can be green, which means it doesn’t have to be dried out and can be cut straight from the tree.
• Leave the bark on.
• Cut the sticks to the length of your tin.
• Pack the tin with thicker pieces to the outer edge and thinner ones in the centre (sometimes it may not be possible it just helps to get an even burn)
• Cover the open end of the tin with the aluminium foil.
• Pierce a small hole in the foil.
• Place the tin on your heat source.
• Smoke will come from the hole when the process begins.
• Keep rotating the tin every so often to make sure all the wood is “cooked”
• It can take between 30 minutes and 2 hours  depending on your heat source.
• Usually it’s done when there is no more smoke coming from the hole.
• Once you take it off the heat let it cool down normally or it might crack.
• If you take the foil off and find it’s not done you can put it back on the heat.

NOTE:
Not every stick you put in the tin will work. It may be too brittle or underdone. I have a 50% success rate which normally gives me about 8 sticks. 

It can be sharpened like a pencil and it's soft enough to make a dense black. One good piece can make three drawings and I use the same piece for all parts of the drawing.

I now use only Hawthone charcoal and make a batch as and when I need it. Here are some examples of what Hawthorne charcoal can do...

One piece of Hawthorn charcoal from start to finish, a homemade "smudger" and the vital "putty" rubber. (I make my smudgers out of old egg boxes just in case you were wondering)