I discovered this while trying out an experimental *cough* medical trainer. Someone else has probably found it by now, but if not, it's too good to not share. I call it the Ninja Trainer; using it, you can pull off:
* unskilled, unarmed civilian dwarf becomes legendary in armor user, fighter, and dodger in less than three months; possible additional stats for armed dwarves (shield/weapon)
* endurance, constitution, agility, and strength maxed out (you've never seen your dwarves move so fast)
* give nobles and children combat skill
* emotionally neutral, no risk
* scalable; number of dwarves you can train at a time is proportional to the amount of wood available
* simple, compact, can be built in a short period of time with basic materials
You will need:
* any flavor of DF2010
* a 3x5 area
* 10 logs
* 2 doors
* 3 mechanisms (+1 for the first trainer), ideally low quality
* carpenter's workshop profiled to dwarf without carpentry skill
Have your carpenter recruit make ten training spears (NOT SPIKES). Then build this:
#####
+|+q#
#####
# wall
+ door
| upright spike
q lever
Fill the spike trap with all ten no-quality spears. The lever is bait; it is not linked to anything. Build another lever somewhere nearby and link it to the spike. It is possible to use a repeater instead, but that is an exercise left to the reader. Profile the lever inside of the trainer to the dwarf you want to train and issue a pull command. Let the dwarf pull it, pause and single-step until he is standing on the spike, then lock both of the doors. Now profile the outer lever to all of the children and nobles in the fort and set a repeating pull job. Each time the spears pop they will harmlessly deflect off the dwarf's clothing, yet quickly build up his skills and attributes.
In 2-3 months you'll have a certified head-chopping ninja. Just make sure to keep an eye on it and let the trainee out to eat and drink every few weeks. It's okay to let them sleep in it; they'll get a negative thought for sleeping on the stone but will sleep soundly in spite of the sticks smacking them in the face.
Obviously, you can build a cluster of these and link them all to the same lever for batch training.
Better than infinite adamantine? Who cares about adamantine when you have a fortress full of bullet-dodging ninjas.