Megaconstruction...
I have one temple made from about 280 marble blocks, 20 gold blocks, with 48 faint yellow diamonds as window decoration, a second made with 32 gold blocks, 20 silver blocks, and 520 marble blocks, and a third (small) temple made with 32 marble blocks, 44 gold blocks, and 8 silver blocks, and a grand road lined with columns made from 230 marble blocks, with a gold statue standing on each of the 36 columns. This is in addition to a 183x4 tile wide wall of solid marble blocks, with a second and third story that are hollowed out to support troops, AND a 12x12, four-story guard tower made from solid gold, doors and all. The common tombs consists of about 550 marble coffins arranged in a spiral pattern, and a small faux-human town outside the gates that's taken nearly 800 logs (all coming from the surface, for that authentic feel). Almost every dwarven dwelling has two marble cabinets, chairs, a table, and a coffer. The dining room has silver furniture, the dungeon is filled with gold chains, and the personal tombs all use whichever metal that noble prefers.
And I still have more marble available than I do nickel and it's every bit as valuable (moreso since it can be used as flux), plus several hundred more gold bars/blocks should I feel the urge to build another monument on the surface. There are better materials to use for megaconstructions.
I suppose I'll just make more bins and then convert all of my remaining marble into blocks to be hauled away by adventurer for later constructions. But I
do like the Two-Face idea, although Two-Face is usually depicted as using a
silver dollar as his coin of choice, which are made of... well, silver.