My characters have a base in near-future Ethiopia. A powerful AI has some of "her" computers there, but the focus is on the people and their attempts to build infrastructure. They've got a machine shop based on the "Global Village Construction Set" including a few lathes, saws &c. Trouble is, they need to defend the place in a few weeks against a rogue general who's sending a hundred or so troops to seize the goodies. This is a ragtag army squad, but absolutely brutal. I can change the details as necessary to make the conflict interesting.
The locals and their Western backers reluctantly decide defense is better than fleeing. What guns and other defenses should they build? I'm thinking Sten guns or Kalashnikovs for their ease of manufacture. Probably, the locals are frightened of the enemy and have the hope (realistic or not) that they can make electric crossbows, remote-controlled traps, and other clever stuff to make up for having limited ammo and few pre-made guns. I can say that the defenders have some ammo of whatever caliber, but it's probably tough to justify them making their own ammo in a hurry even with all the formulas and machinery. They need confidence-builders as well as hardware.
In short: What should these guys build to help poorly-trained villagers drive away a ruthless maniac warlord?