This is the Save for the Beastdiamonds fortress, with its delightful Vile dust clouds.

The fort is on a Terrifying Glacier.
To make the bolts as it stands:
1)mass dump bolts outside
2) wait for a cloud to move across the squares containing them
3) Retreive said bolts -make sure to unforbid them after the clouds gone-
4)????
5)PROFIT!

Currently at around 100 dwarves, the gen has been modded for extra dragons who mature in 5 years.
The fortress is only a few years -i think this may be the third- in, so its easy for you to set up your own game if you like it enought enjoy!