PrestaShop 1.6.x. How to set up attributes that impact on products price

1. In your PrestaShop admin panel go to Catalog-> Products section: 
2. Click the Edit button near the product you want to add the attribute to: 
3.  Click the Combination tab on the left: 

There are two ways to add combinations to your product:

Automatic Method

1. To generate all of the combinations and possibilities automatically, click Product Combinations generator:
2. To add an attribute value to a combination, click on it (hold Ctrl to select more than one at a time). Click the Add button at the bottom to confirm the action: 
3. You can change the price/weight of the value.  Select a default quantity (it is supposed to be the same for every combination) and default reference if you need it. To save the changes, click Generate These Combinations button: 
4. If you want to remove all generated combinations, you can click Edit button and select Delete. You can also make the selected combination as the default one: 

Manual Method

1. To add a new combination, click the New Combination button at the bottom of the page: 
2. On the next page, from the Attribute drop-down menu, you can choose a group of attributes. From the Value drop-down menu choose the attribute value that you would like to include. Click the Add button: 
You can add as many attribute-value as it necessary for one combination. You can add only one combination per type of the attribute.
3. You can also set the following settings:
   • EAN-13 and/or UPC barcode – indicate the combinations reference;
   • Wholesale price – the field is useful if the original price of the product changes because this is a combination;
   • Impact on price/weight/unit price – choose the appropriate drop-down menu, select “Increase” or “Reduction” depending on the context, and fill the field that appears with the value of that impact;
   • Minimum quantity – set the number of items to be sold in bulk.
   • Available date – set the available date when this product is out of stock;
   • Image – select the images that are linked to the original product;
   • Default – check this box if you want the current combination to actually be the main product.
     
4. Click the Quantities tab on the left to set the desired number of product items with the created attribute to appear in stock:
   
5. Refresh your website to see the changes. Your combination will appear in the attributes list.

Hopefully, this tutorial was helpful for you.