you would need to add a new column to the cart object called "shippable".
for the items shipping should apply to, set the shippable column to 1 in the add to cart buttons.
for the items shipping should not apply to, set the shippable column to 0 in the add to cart button.
then in the shipping rules, you will need to use the custom condition trigger option and add the following code:
$this->ConditionalTotal("Quantity", "shippable", "1")
for example, the trigger for the 1meter rule will be:
$this->ConditionalTotal("Quantity", "shippable", "1") == 1
the trigger for the 2 - 20 meter rule would be:
$this->ConditionalTotal("Quantity", "shippable", "1") >= 2
AND
$this->ConditionalTotal("Quantity", "shippable", "1") <= 20