About half of your work is done in Setup, where you create fields on multiple objects and update picklists. Then make a configuration attribute related to the Solar Controller Hub product. Next, create global attributes, attribute items, and an attribute set. Finally, relate the attribute set to all three mounting kit options on the Solar Controller Hub product. Units 1, 2, 5, and 7 in the Personalize Smartwatches with Salesforce CPQ Attributes badge are especially helpful here.