Similar to the shape of Elon Musk's Hyperloop.
Tested and run through a long tube like the Hyperloop.
A battery powered vehicle that is propelled using a fan.
Contains eggs in order to test the vehicle's safety.

Supplies

cardboard poster tube
2 medium eggs
foam
wood
fan with motor
2 sandwich bags
servo
wooden dowel
battery
velcro
receiver
controller
cardboard
masking tape

Step 1: Cut Tube.

Cut cardboard poster tube to 40cm length.
Cut a 10cm diagonal slant at the front end.
Cut 2 slits at the back end of the tube - creating a top piece that can be lifted up in order to see inside the vehicle.

Step 2: Cut Panel.

Cut a rectangle (9cm x 6.5cm) out of the tube 3cm from the end of the slant.

Step 3: Cut Hole in Lid.

Cut a circular hole in the plastic lid of the tube.
Ensure that the fan can sit tightly in the hole.
Use the masking tape, when wanting to run the vehicle, to keep the back of the cardboard tube tight around the plastic lid (as the lift piece made at the back of the tube means the lid no longer stays on the back).

Step 4: Make Egg Holder.

Copy the photos.
Make 2 foam pieces that when put together can contain 2 eggs and fit tightly in the tube.
Sandwich bags are used to contain the mess of the eggs when testing the vehicle.

Step 5: Make Brake System (Crank and Slider).

Cut a wooden stand with a rectangular gap for the serve to sit in. It should have a curved base so that it can be glued evenly onto the curved surface of the tube.
Cut out a small wooden circle (approx. 3cm diameter) with a hole in the centre that will fit the rotating piece of the servo tightly into it and another hole near the edge of the circle. (This part was made using laser cutting, however, it is viable to be made by hand.)
Fit the wooden circular piece onto the moving servo part.
Attach the wooden dowel to the rotating circular piece using wire that is fed through the whole near the edge of the circle.
The wooden dowel should be guided through a large rectangular cardboard piece (which is glued to the vehicle's inside body) and a small wooden piece that is glued to the braking panel before reaching the braking panel itself, which it should be glued to. (The cardboard piece and small wooden piece is used to keep the breaking panel steady and support the wooden dowel.)
Ensure that the wooden dowel does not stick out past the breaking panel.
Lastly, cut of a piece of foam that sits inside the tube. This will act as a buffer and protect the battery.

You have now created a crank and slider mechanism. Using the servo's rotational movement, the wooden dowel pushes out the breaking panel when needed. This will hit the wall of the tube that our vehicle is running through and create friction, stopping the vehicle.