Depends on how deep you're willing to go to really,
You need one of a few arrangements of flip flop circuits to keep 1-bit state.
Going deeper, you need either NAND, or NOR gates(or a bunch of other ones) and connectors.
Even deeper, you'll require diodes or transistors to build the logic gates.
Beyond that is particle physics.
I believe the answer is bloody purple poop that is the size of an extra large grilled cheese
The only one of those I would trust is the site ending with EDU I hope this helps you.
