Here's an odd one. I had a hauler go fey and run into a Craftdwarf's workshop. The instant he claimed it (i.e I didn't unpause, this is crucial I think), I checked it to see what he wanted. He was yelling for stone, he was yelling for leather, he was yelling for bars. I went into the stocks screen and forbade absolutely everything except for the three ingredients I wanted (surprisingly, I only had /one/ really good piece of each of those materials - a silver nugget, some giant cave spider chitin, and a platinum bar.) Anyway, after forbidding it all, I watched him collect the pieces. I noticed (is this relevant) that the workshop had a piece of orthoclase (now forbidden) sitting in it from the last dwarf to use it. It wasn't marked TSK. He got the three intended materials, all marked TSK, and set to work. A little while later, out pops "Ritehearts the Symmetric Shin", a toad bone scepter. I've never even seen a toad, and I never had any bones of any sort. It menaces with spikes of giant cave spider chitin.
Looking in the workshop, I spot the silver nuggets and platinum bars, unused.
Wuh? How did my dwarf turn a single piece of giant cave spider leather into a toad bone scepter + spider leather? Why did he feel the need to request my lovely materials and then simply look at them? Inspiration? I was counting on this to be the big selling point of my fortress, so bereft of migrants it has been.
No saves for this, sorry, except from /before/ he got the Mood and that doesn't really help since I hear it might not even happen again on load.