Do-It-Yourself/Ionic wind thruster
An ionic wind thruster is a booster based on ionizing air to create thrust. These thrusters work by adding an electron to a particle of air so that the air is forced away from a the negatively charged grid. This produces a level of thrust T=mv, with T being thrust, m being the mass of the air, and v being the velocity of the air.
A common science fair project may be using a charged grid to 'levitate' an object several decimeters above a surface; more interesting applications may include levitating the hull of a car and building something more akin to Luke Skywalker's speeder or a hoverboard as seen in Back to the Future 2.
The basic design involves using a 555 timer to repeatedly and rapidly pulse a high voltage, low current electrical charge through a grid of wire. Typical values would be 30,000V at 0.001A, or 30kV at 1mA. This is typically enough power to levitate a small grid on its own; however, the grid can be combined with a light-weight plastic skirt or cone to better control the thrust angle and create backpressure. The function of such a cone would be to prevent air from going out sideways, which decreases the amount of thrust in the direction we want; however, too much backpressure will also overpower the total thrust of the system and negate the effect.