When you click your Post production tab in Materials, you see this: 

In the "Add custom post production type", you can write anything you want. For my 3DP printer, e.g.  I've added different types of post-printing coatings: 

How to add another one: Step 1: In the title I write the name in a way that is clear enough for me, simply using the trade name of the coating involved: 

I choose the "pay per cm2" pricing option, and from experience, I input a price, which should reflect a: the cost per liter and the consumption per cm2 of the model, b: the time I spend on average per cm2 of a model when coating with this material; 

Since "ColorBond" doesn't tell my customer much, I try to invent a name for this option myself, to input in the "Name for user" field, e.g.: "Bright and Strong"
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And for the "Note for user" I copy from the Manufacturer's specs:
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So I add: "Improved strength and color vibrancy."
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Step 2: I click "Add". The new custom type "Colourbond coating" is now saved, and a new blank for another Custom post production type opens.
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Step 3: To make my new type active (available to the customer), I tick the box left of the option:
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And I save the tab:
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This is what it will look like on the widget: 

Please note: You will have to trust that the customer knows that he can choose only one of these options.