This is a list I’ve complied of what the Diamonds might have made, or which diamonds made these specific places/objects.
WARNING: Extremely long post
Rose/Pink Diamond:

Rose’s Fountain: Passive, A sacred sanctuary used to heal gems.

Ancient Gem Colony Ship: Passive/Aggressive, Used to reach new planets to set up warp pads, filled with death traps placed there possibly to keep intruders out.
May have been a collaboration between White and Pink Diamond.

Rose’s Secret Armory: Passive, full of weapons, armor, and a giant penny.

Laser Light Cannons: Aggressive, powerful magical cannons.
White Diamond:

Pyramid Temple: Aggressive, full of death traps, powered by a trapped gem. That gem may possibly be White Diamond herself.

Robot Shooty Thing: Aggressive, a robot that has 4 forms: Flame, ???, Electricity, and Ice.
Extra note: It has White Diamond’s face markings from the Mural and the Obelisk head.
Blue Diamond

Lunar Sea Spire: Passive, was an oasis for gems on earth.

Communication Hub: Passive, used to send messages between gems over long distances.
May have been a collaboration between White and Blue Diamond.

Galaxy Warp: Passive, a central hub for interstellar transport used by gems.

Sea Shrine: Passive/Aggressive, it is filled with various hourglasses. If any hourglass other than the correct hourglass is tampered with the Sea Shrine floods.
Yellow Diamond:

Gem Warship: Aggressive, used to travel from Homeworld to Earth, shoots lasers.

Kindergarten/Facet Five: Aggressive/Passive, used to make new gems.
May have been used by all of the Diamonds.
That’s what I think the Diamonds may have possibly made.
If you have any other ideas, feel free to add them!
