it is a big wheel that roles with a motor INSIDE

Step 1: The Spokes

you need to make 16 of them

Step 2: Rolling Strip

this touches the ground
you need to make it exactly as I say:

blue rod = b
white rod = w
and yellow connector = +

+b+b+w+b+b+b+b+b+w+b+b+b+b+b+w+b+w+b+b+b+b+b+w+b+b+b+b+w+b+b+b+b

and make it twiece

Step 3: The Motor

just follow the pictures

picture 8: their are 4 grey spacers

Step 4: Putting It Al Together

OK...
first place place those 16 spokes on the yellow connector with between two spokes a connector between. and the yellow connector you haf left, connect them to eachother with red rods.

second, you need two snowflocs for each side, adn put it togeter like this

third and last step, put the motor in and...

LETS ROLL

sorry for my bad english. Im from belgium