Hi there,
In the mechanica of heron it is mentioned that the temperament of the Simulacrum is determined by the material of construction. I have to ask then.... what personality is associated with each metal in Ars? I have no idea where to search for it. 
Any references please? I am specially interested in gold, silver and electrum (gold and silver mix). The personality of rubies (I guess choleric), emeralds and topazs would also be appreciated. 
Cheers,
Xavi
Although it is not remotely based on genuine 1220 belief, I use new-age, hippie, crystal healing sites for inspiration for this kind of thing.
Like this one...http://crystal-cure.com/color-meanings.html, if you look at each colour it tells you the personality traits and the gemstones apparently associated with it.
I was going to suggest looking at the Metallic Dragons from D&D since IIRC they were pretty close to the traits associated with different metals, but perhaps Richard's suggestion might be better since they likely have the same ultimate source anyway.
Here's a new agey site with a strong focus of metals: whats-your-sign.com/elementa ... mbols.html
Edit: This place seems pretty good too though I haven't investigated too deeply yet: symboldictionary.net/?s=silver
More near Hemeticism put bonds beetwen Astrologic and Alchemy, so you could stablish Planets and Metals. Founded here:
es.wikipedia.org/wiki/Astrolog%C3%ADa_y_alquimia
Sun - Gold
Moon - Silver
Venus - Copper
Mars - Iron
Jupiter - Tin
Mercury - Mercury
Saturn - Lead
No idea about the others, but on Ars & Academe can be founded the propietys of others materials, and then use that like personality (Choleric and so on)
Start with the Form and Effect bonus chart, the one on this website. Gold is listed as Nobility and Peace, for example. If your material does not give a personality trait, then use it and hope for the best, and you have a direction for researching a new Form and Effect bonus.....