|This stove weighs approximately 100 grams and takes practically no space at all. It is made of 0.4 mm thick titanium sheet metal, which is lightweight for its strength, and can withstand the high temperature of a wood-burning fire. Aluminum would also do fine, but it melts too easily.|
It packs away flat, and is assembled in a minute. The stove has four
walls and a raised bottom, and is designed to be used with a pakki,
a tall, slightly flat cooking pot popular among Finnish hikers.
I think it's called a "mess kit" in other languages? This design is
compatible with both the Finnish army pakki, as well as the other
common variant, the "Swedish" pakki—the major
difference in the Swedish version being a single protrusion that requires
the slot in the top edge of the back plate of the stove. (The Finnish
pakki, being aluminum, is somewhat lighter than the Swedish
pakki, which is made of steel.)
To assemble, first attach the two sides to the back. Spread the sides a bit to insert the bottom. Finally attach the front, which locks everything else in place. Of course, when first heated, the sheet metal twists completely out of shape, but the locking tabs do work even so.
Here's the stove in use, burning dry twigs. It can also be used with
a Trangia spirit burner, which may be used indoors or under a tent
flap, but the less fuel you need to carry with you, the lighter your
backpack will be.
The stove works just fine in windy weather, but with no wind, you'll end up blowing constantly in the fire to keep it going. The fire space should be a couple of cm taller, which would make it burn easier (see my later modification below). Also, a lot of tar and other unburnt residues condense on the pakki, making it sticky and rather messy...
This thing has served me well for some 14 years (as of 2023). The sheet
metal has deformed back and forth quite a bit, but the pieces still attach
together as designed. I did, however, grow tired of having to blow on the fire
constantly, due to the too small space allocated for it.
Thus I have later modified the design (not updated to the CAD drawings, sorry) with two additional support plates, 3 cm × 14 cm each, which go between the two raised sides. Look at these photos of the support plates in place and removed and you'll see where they go. In the latter photo you'll also see the slots I cut to fit them in. They raise the bottom of the pakki from its original recess (as in the above photo) to the level of the raised sides (as seen here), giving 5 cm more room for the fire. You can see this makes a world of difference! Whereas this "turbo" arrangement can consume a bit more firewood, it does also burn a lot better, requiring less blowing and other maintenance. I now use this arrangement pretty much exclusively, unless I'm using the Trangia spirit burner instead of twigs. Despite being a bit higher than the original, the raised design remains quite stable. The new design will also work with any flat-bottomed pot, not just the "skinny" shaped pakki.