Several suggestions

[septemberWaves]

Here's just a few things which might be nice to add to whichever relevant Metals mod:

• Bismuth texture change from plain white to a greyish-greenish-blueish colour (e.g. something like hex colour #91edd6)
• Osmiridium alloy of iridium and osmium
• Scandium metal and scandium-aluminium alloy (scandium being very rare, the alloy tools would have very high durability)
• Solder alloy (possibly made from antimony+tin or antimony+lead), could probably be similar to mercury with having a liquid state
• New items that could be made from metals: ball, sheet (like the glass pane but made from metal), wire (as a crafting component), mesh

[dshadowwolf]

Some of this (the alloys) are things we'll likely follow-up on - if not in the 2.5 release, then in 3.0
(Osmiridium, Scandium and the Scandium-Aluminum alloy are going on the list right now - the rest will need discussion by the team)

[jriwanek]

Solder is already provided in the advantage series.