Materials used:

Old boiler/geyser barrel.

Fire bricks for the burn chamber.

All other bricks are standard bricks.

Ceramic fibre board for the riser inside the barrel.

Clay and sand mortar between all standard bricks.

Fire-cement (very tiny amount) between burn chamber fire bricks.

Cob plaster to seal barrel and around burn chamber.

(All bricks will eventually be cobbed).