Product Variations Problem

I am using WooCommerce for my wordpress site, making an online Vapor Shop catalog for a customer. I want to be able to have a dorp down menu for the size of the e liquid bottles which is either 15ml or 30 ml each price is the same for every flavor, but also want to have a dorp down menu for the “blend” and “nicotine level” that would not alter the price in any way, but is more for the vapor shops reference for them to make that blend and nicotine level. How do I go about doing this…stuck :(, Basically looking for an easier way than linking all the variations, because of the fact the price only changes from the size of two dif bottles and not the other two attribute factors.