The basic principle is get a bigger container to put a smaller container in. You make the fire in the bigger container and put the wood you want to gasify in the smaller one. The fire has to be larger than the amount of material you want to gasify.
How I did it:
First I bought a empty 1 Gal & 1 Qt paint can. Then bought a 3/8" by 6 or 8" nipple (pipe with threads on both ends) and a coupler for installing conduit into a junction box for electrical outlets.
Then ream out a hole a little smaller than the pipe your trying to attach into the top of the 1Qt can with a drill and screwed the conduit and pipe in nice and tight. I didn't even have to use the nut to attach it to the can top.
Then drill 6 holes into the 1Gal can to put three rods across the can, for the 1Qt can to sit on. Try to make the top of both cans the same level. Then I busted up a piece of 1" think block and put them on the four sides inside the 1Gal can, to hold the 1Qt can nice and tight.
Then drill a hole in the bottom of the 1Gal can and cut out a rectangular opening at the bottom of the 1Gal can with tin snips and fold it up inside the can. It should look something like this.
You're all set. Here's two angles of the finished gizmo.
Time to try it.
Here's the material I used.
A little glop on dryer lint. A Swedish Firesteel. And three different sizes of wood.
I started the lint of fire on my stone steps with the Firesteel.
Once it was going (after a few strikes) I picked it up and threw it into the hole in the 1Gal can.You can see a little of the fire under my pinky.
Then throw in your smallest pieces of wood and get it going.
It only took 3-4 minutes and I tried lighting it.
After a couple of tries it light!
Mission Complete!
Now I have to build a bigger version and either attach it to this old lawn mower I have or run a hose from the gasifier to it and see what happens. Also need to make some kind of filter to filter out the tars and ash.
Oh, forgot to mention I used small wood chips from planeing a drawer for this, since it was a small version. It was basically large saw dust. But the wood in the gasifying chamber should be smaller than the wood in the fire chamber.