Add Drop down choice metafield to product

[lindsaysff]

Hello, 

I would like to create a product metafield so that a customer can choose from a list of predefined choices. This wont apply for every product and the choices for each product will be different. I would like the customer's choice to show up in the cart and in the order note I get so that I know what their choice was. 

I have already done this by building a theme template for specific products, but I would like to be able to change his within the product meta fields instead. 

I have done it using a custom liquid block, but then I can't get it to show up in the order so that I know what they chose. Please help me. 

For clarity, I am making mugs and I would like the customer to choose what they would like on the left or right side of the mug. 

Thank you so much for your help