A nice house for myself.

[removed]

Water purification systems.
Sustainable renewable energy systems.

Iron man Real Life suit with all its functions (those that are possible atleast)

A reddit party house

Some kind of vessel that can go to the bottom of the deepest depths of the ocean without cracking under the water pressure.

An underground pneumatic tube highway system across America that can swoosh a car from LA to Chicago in under an hour.

A University for development of practicle small scale water filtration systems, emission free power generation and power storage solutions. 🤔