Craft Commerce: Product Options
Normally you would create variations of a product that would then be purchased by a customer. An example could be a plain t-shirt (the product), which is available in small, medium &amp; large (each of these would be a variant of the product). This way you can easily keep track of stock, set different prices (like your No. of meters) and add different field values, if needed.

I would create a variant for each "No. of meters" as this will require a different price to be charged. However, creating a variant for each and every configuration would be overkill. 

As you don't need to track stock and each product will be made to order I would instead look at adding the options to the line item using name="options[optionName]".

The following is taken from the default templates that come with Craft Commerce.

&lt;select name="options[giftWrapped]"&gt;
  &lt;option value="no"&gt;No gift wrap.&lt;/option&gt;
  &lt;option value="yes"&gt;Gift wrapped.&lt;/option&gt;
&lt;/select&gt;


These options are then set on the line item for that order. These would be viewable on the order summary page in the control panel.