Appropriate design for local needs depends on local conditions.
I haven't been to Afghanistan. If you want to get back to me about local conditions, I'd be happy to help tailor a set of instructions that your guys can work with.
From my 'armchair,' I get the impression that Afghanistan is arid and mountainous, with limited areas fertile
enough for commercial agriculture.
Arid, hilly regions in the US west often have excellent subsoils for making adobe or cob, but fuel is scarce.
Firing bricks uses a ton of fuel. Might be a problem if you're trying to help the locals with low-fuel stoves. If it's economical to fire bricks there, locals will have a method and access to bricks. If not, it may be more trouble than it's worth. Insulative bricks can be created without firing, either by using cement or by building in place with minimal transport.
Local ash can certainly be a good insulator. Sawdust and clay make an insulative foam (the sawdust burns out, leaving holes). Local agricultural wastes like wheat chaff could be used in the same way, mixed thoroughly with local clay slip.
I'd also look to local waste products for forms and liners - like your coffee can example. If a special tin kit gets shipped over, it will be hard to replicate locally. There are probably some ubiquitous scrap materials that will still be plentiful after the Army leaves, and these would be a good source for liners.
Some of the SE Asian fruit drinks, for example, come in very sturdy steel cans for extended shipping. If those are also common in Afghanistan, try them as a cylindrical liner for a tiny portable stove chimney, with a larger can around the outside. Rectangular steel cans from kerosene or cooking oil can also be handy, if they are locally disposable rather than reused.
One risk I see with this approach is that it could seem 'junky.' Earthen bricks might fit in better, and be easier to maintain locally once the liaisons are gone.
India has "the Good Stove"
http://www.e-goodstove.blogspot.com/ .
2-pot stoves are preferred for local cooking needs in India and Latin America:
http://e-twopotstoves.blogspot.com/, and some of them even have chimneys.
You may not get a completely clean burn with any of these small stoves. Approvecho
http://www.aprovecho.org/lab/index.php has been developing variations on insulated metal stoves for years. (They
sell kits / instructions too.) They are aiming for clean air, but they all put out some amount of soot. A chimney on the stove, or a hearth vent, can help reduce indoor smoke in cold regions.
There's also a
thread on these forums for a "fox stove" that you dig into the ground for camp cooking. Can be useful for folks on the move.
Your guys on the ground may find the locals are pretty sophisticated about fire; more so than most Americans, who have the utilities to fall back on. As long as they're willing to learn as well as teach, it could be a great cultural outreach
project.
Ernie points out that sheet metal in a war zone can be salvaged from munitions as well as canned goods. In Pakistan, this historically included children going out to collect both spent and unexploded shells for their brass casings.
This is likely to happen regardless of stove design, but it might be a consideration in promoting brick vs. metal.
So: questions about local conditions:
1) What foods are they cooking, and how? Fried, baked, boiled, steamed?
2) What do the current local stoves look like? Are they indoors or outdoors?
3) What fuels are commonly used?
4) What materials do they have on hand? Junkpile, barnyard, dump, rag-pickers?
5) What secondary use do they expect from a cookstove? eg home heating, portable, trash disposal, aesthetics, etc.
Cultural Considerations:
6) Do they share communal kitchens/bakeries, or is cooking done in each small household?
7) Does the liaison team have the ability to work directly with Afghani women/cooks? Helps if there are women and/or cooks on the team. Teams working in Africa who talked to the men (not the cooks) were
led astray by uninformed opinion and enthusiasm, and the resulting stoves were pushed on the women but not widely accepted or replicated.

Who builds the stoves? Cooks, family members, the community, or specialists?
These are the questions we'd be asking if we were on the ground. Knowing the answers can make or break the appropriateness of a new cooking technology.
Hope this helps.
If you've already considered these things and just want kits, please get in touch. We can help create instructions and other flat-packable supplements to the materials on the ground.
Best of luck with the project. Please let us know how it goes!
Yours
-Erica and Ernie Wisner
http://www.ErnieAndErica.info 503-758-1093
Questions @ ErnieAndErica.info