Make a Foil Roller Coaster

You can make a roller coaster using just a few items.

Steps

Take some foil, about the length of your arm span, and fold it in half.
Fold it in half again.
Fold the long edges of the foil, about an inch each time, toward the middle. Do this twice on each side.
With what you have folded down on each side, fold that section of foil upward, so it is like a tunnel without the top.
Tape one end of the foil to something like the top of a chair, so the foil is a slope.
Tape the foil down to something about half the size of the chair so that the foil is supported by it. Make as many of these slopes as you'd like. You might want to anchor this supporter to the ground in some way as well.
Fold up the very end of the foil to keep the marble from going anywhere.
Try to make the roller coaster as smooth as possible.
Finished.

Don't worry if it doesn't work the first time you send the marble down! There may be some bumps that have stopped it or made it fall out. Smooth them out and if that does not work add more vegetable oil.
Don't make the initial slope too steep - otherwise the marble just falls and all speed is lost on impact at the bottom.
It also helps if you have the size of a full pumpkin, so that you can actually make the size of a roller-coaster, (a mini one) and put the marbles in there!
Conversely, if the initial slope isn't steep enough, then the marble won't gather enough speed to go through loops or turns and things like that.
It helps to have more than one person for assistance.

Tinfoil can have sharp edges. Be careful when folding it.
Making the roller coaster turn can be very difficult. Banked (tilted) turns are sometimes easier to accomplish.