Lithoform Engine and Sands of Time on the battlefield.
Artifacts, creatures, and/or lands that can tap for at least ({3} magic symbol) .
Steps
At the beginning of any upkeep step, Sands of Time will trigger.
In response to that trigger, tap all of your lands, artifacts, and creatures that can produce mana, then tap Lithoform Engine, copying the Sands of Time trigger.
Allow the trigger to resolve, untapping your mana producing permanents and Lithoform Engine.