How do you associate a Material Picker to prefab placed in scene from AssetBundles

Today i am writing to inquire about a strategy to solve my next challenge. I am using Vuforia AR to place a Prefab into the active scene. These Prefabs are not in the scene upon start/runtime, rather are extracted from an Asset Bundle after a button click event. And once placed, utilizing LeanTouch+ to accomplish the manipulations.

New Challenge

I would like to be able to have in the UI, a material picker used to change the Material of a placed Prefab. Because these Prefabs are not in the scene until pulled and placed from an AssetBundle, there is no active association between the ColorPicker and the Placed Prefab at start of runtime

The Question

Given that we are already using multiple gestures/fingers to perform the manipulations, how would you recommend we use LeanTouch to "select" the Prefab in such a way that it will associate it to the ColorPicker and be able to apply the material change to the model in the Prefab

I am looking for a strategy, and certainly don't presume that the solution specifics. But i am struggling to know where to start to solve this challenge.