The most complete list of official special materials published for Dungeons and Dragons 3.5 that I could find is the user terronus's salvaged-from-the-Wizards-of-the-Coast-forums Special Materials Index here, hosted on the Giant in the Playground forums.
Although terronus's Special Materials Index really should be sufficient for most campaigns, keep in mind that even it omits, for example, special materials from the Bazaar of the Bizarre column "Secrets of the Master Smiths" (Dragon Annual #5 38-40), the special material ferroplasm (Psionics Handbook 138), and the special material nepthelium (Sunless Citadel 32), this last so obscure I was unaware of it until finding this thread (also a valuable resource yet less navigable). (So you needn't look it up, metal weapons and armor made from nepthelium cost 100 gp more and appear transparent or gemlike; this has no mechanical effects.)
The d20PFSRD compiles Pathfinder's ever-growing list of 1st- and 3rd-party special materials here.
Maybe a weapon made of ferroplasm will do?
Mined from secret locations in the Astral Plane, this malleable metal holds its shape only in the hands of a psionic being. When an item forged with ferroplasm is unattended or held by a nonpsionic creature, it melts and temporarily loses all special powers. But when wielded by, psionic creature, such an item immediately springs bad into its true shape and regains all abilities. In its proper form, a ferroplasm item glows with a violet light (illuminating a 10-foot-radius), unless the item’s owner mentally quenches it. In an area where psionic powers do not function, it collapses as if in the hands of a nonpsionic creature. ...
Weapons fashioned from ferroplasm have a natural enhancement bonus to attack and damage.... These bonuses do not stack with other enhancement bonuses. Weapons or armor fashioned from ferroplasm are treated as masterwork items with regard to creation times, but the masterwork quality does not affect the enhancement bonus of weapons....
Ferroplasm has hardness 20 and 40 hit points per inch of thickness when in its true form, and a hardness of 5 and 10 hit points per inch of thickness when soft. (Psionics Handbook 138)1
A weapon made of ferroplasm that deals 1d4 or 1d6 points of damage gains a +1 enhancement bonus and costs an additional 2,500 gp, while a weapon made of ferroplasm that deals 1d8, 1d10, or 1d12 points of damage gains a +2 enhancement bonus and costs an additional 7,500 gp.
Alternatively, how about a sentira weapon?
This bizarre material is wrought by Chosen, Inspired, and (rarely) kalashtar who use powdered crystal and the power of their thoughts and emotions, also drawing on the essence of Dal Quor. Sentira items are literally grown into their final form. They have an organic,
whorled appearance, much like horn or shell, with a shimmering, opalescent surface. Color varies based on the emotion used to create the particular batch.
Sentira is lightweight and almost unbreakable. Because of its resonant properties, it is an ideal material for emotional armor. For purposes other than those described in this chapter, sentira is treated as mithral.
Sentira can be formed, sculpted, and repaired only by psionic creatures that have the Craft (sentira) skill. Such craftspersons, known in Riedra as thoughtweavers, must expend 1 power point for each day of work on a sentira object, whether building or repairing it. (Secrets of Sarlona 135)
Sentira is, you'll note, made of "powdered crystal" but "treated as mithril"--I don't know if that's close enough for the DM (or a chem professor), but at least the description mentions another metal, albeit a fictional one. Interestingly, although no statistics are given for making weapons from the sentira, everything else in Secrets of Sarlona is made of sentira (e.g. armor, mosaics, gates, public art installations, passports, entire buildings). It'll be up to the DM to determine the price of sentira weapon. I suggest he be guided by the special abilities and costs of emotional armor (137-8).
- Yes, the Psionics Handbook, not the Expanded Psionics Handbook. The special material ferroplasm doesn't appear to have been republished for Dungeons and Dragons 3.5 making the Psionics Handbook version oddly Dungeons and Dragons 3.5 compliant.
Best Answer
You can't just physically make a weapon out of more than one special material. However, there are some weapon enchantments that can provide that benefit:
Transmuting. Price: +2. Sourcebook: MIC.
The weapon automatically changes itself to gain any or all of the following properties as needed, after you hit an enemy with the corresponding DR: adamantine, cold iron, silver, bludgeoning, piercing, slashing, chaotic, evil, good, and lawful. This change isn't fast enough to apply to the same attack that triggered it, only to subsequent attacks in the same encounter. Only for the purpose of DR, so adamantine mode doesn't bypass hardness. (This might be what you're thinking of with "inlaid", since the fluff describes it that way.)
Metalline. Price: +2. Sourcebook: MIC.
You can change the weapon's material between adamantine, cold iron, or silver. This costs a standard action, and it can only be one of them at a time. (In adamantine mode, this does have adamantine's hardness-penetrating property. But it's weaker than Transmuting in every other respect.)
Shadow Striking. Price: +3. Sourcebook: TOM.
The weapon overcomes all material and/or alignment-based DR. (Unlike Transmuting, there is no delay in adapting. But this doesn't provide B/P/S damage types.)
And finally, you could combine one of the above enchantments with an actual material that provides some bonus other than overcoming DR, for a total of four effective materials.