I am currently working on a study and I want to know the challenges/problems faced when 3D printing additional polymer features and structures over/on top of previously injection-molded plastic parts in a way that there is a good adhesion between the underlying injection molded part and the overlying 3D printed structure.

If this is possible then would I have to pre-treat the injection molded part? What kind of treatments would they be?

I found Voxel8 and Arburgh’s Freeformer to be somewhat relevant, but can’t quite grasp the inner intricacies of its configuration.

Any help would be greatly appreciated! Thanks in advance!