Use Mouse.TargetFilter and the hit detection will go through that part, meaning that part was ignored. Based on the image, I assume you’re also ray-casting, you can use WorldRoot:Raycast with a RaycastParams object. RaycastParams allows for filtering using FilterDescendantsInstances and can be set to it’s respective whitelist type with FilterType
If you ever need to filter multiple instances while still using the legacy mouse object you can parent them all to a single folder instance and filter that instead.
Mouse.TargetFilter = Folder --Folder of instances to filter.