The Ravenna Ultra-Low-Altitude Vehicle: A Rocketship Treehouse – the makers write -

Rarely does building a treehouse require welding, grinding, painting, riveting, bending, crimping, plumbing, brazing, laser cutting, sound design, printed circuit board fabrication, thousands of lines of C code, distributed network protocols, sewing and embroidery.

Ours did.

The RULAV is a hexagonal capsule, 7.5 feet (2.3 meters) high, atop a tripod 7.5 feet (2.3 meters) high, for an overall height of about 15 feet (4.6 meters). It is about 6.5 feet (2 meters) across at its widest point. The frame is welded mild steel with riveted aluminum skin. It contains nearly 800 LEDs forming dozens of numeric displays spread across 14 control panels, each with an acrylic face laser-cut and etched with labels such as “Lunar Distance” and “Hydraulic Pressure”. The pilot controls the rocket using a joystick and panels full of working switches, knobs and buttons. Underneath the capsule are three “thrusters” that shoot plumes of water and compressed air under the control of the pilot’s joystick, simulating real positioning thrusters. Takeoff and docking sequences are augmented by a paint-shaker that simulates the vibration of a rocket engine. Sound effects complete the illusion, with a powered subwoofer that gives the rocket a satisfying rumble.