This is willow charcoal I made. The willow trees need coppicing (chopping down) each winter and I took some sticks and pealed the bark off them.
This is an old tin something, maybe chocolates? With a nail, puncture the hole in it. fill it as tight as possible with sticks (green is fine, dry is better) and wrap some stiff wire around it to make sure it stays closed. Toss it in the woodstove at the end of the day. It's ready by morning.
Considering, with shipping and stuff, it's about a dollar a stick to buy this kind of willow charcoal, I expected it to be more difficult to make.