It is for a science project and would somehow need to be able to carry a marble uphill.
864 dollars 24feet / 3 feet per yard = 8 yards 18 feet / 3 feet per yard = 6 yards 8 yards*6yards = 48 square yards * $18 = $864
you could buy one but there not cheap now if it for school you can make one try to find a old belt check with some auto repair shop for a serpenten belt used turn it inside out for your marble it should work
Pop into maplins (uk, google them) (us, try radio shack) purchase one of their cheapo gear and pulley kits and a cheap electric motor, say 3v. Take two small blocks of wood and cut a v shaped groove in them. Take an axle and two wheels, assemble them together so the wheels are slightly in from the end of the axle. Rest the ends of the axle on the two grooved v blocks. Take a strip of rubber to the dimensions you need, obviously doubling the length. Wrap it around the axle then glue the other end together. Make a similar construction for the other end, only higher. Make sure to slot the axle through the 'belt' before putting the second set of wheels on. On either sets of wheels, you will need to also put a grooved cog wheel, then a smaller or larger cog on the motor. (Smaller to increase motor speed, larger to decrease it). Mount the motor so it fits the cogs, and voila, convey away.
i okorder and look at how escalators or belt sanders work. Who knows, you might be able to just use a belt sander to do the project somehow!
look at toy tanks and bulldozers. I think you may be able to find one with the right size caterpillar treads. .
