What is this adventure where the party is stuck in a dungeon with a time machine?

Question

I used to DM for a group in high school and ran a great adventure that involved everyone being stuck in a dungeon with a machine that allowed the party to travel back and forth in time. It was a bit of work keeping track of things changing through the timelines but a great puzzle adventure. I would love to try it again now, but I have had no luck finding it.

What I remember of the adventure:

• It was in D&D 3.5e.
• The mechanism for time travel was a bridge in a cube-shaped room. The bridge could move, and you would walk to the other wall (and gravity would change for you and all); each wall was a different time period.
• There was a magic 'elevator' - essentially a hole you jumped down that would loop back up to the top with a portal. If you held the right beads, you would stop at the desired floor.

Answer 1

Hickman's "Anvil of Time" (Dungeon #86 13–43)

Dungeon #86 (May/June 2001) includes Tracy Hickman's "The Anvil of Time" (13–43) for Dungeons & Dragons, Third Edition. (This adventure dates to well before the Dragonlance novels series of the same name.)

The adventure is set in Krynn and involves time travel like the question describes… and to say anything else would kind of ruin the adventure. Suffice it to say, it matches your memory, down to the very specific bead-dependent magic elevator, plus it includes a black-and-white line-art illustration of how many beads it takes to reach each floor:

^{Tip: Do not attempt without beads!}