Hi @Marruger, sounds like a fun project! 
@slensgra posted recently about a project with a modified gripper - there’s some more information in the manipulator section of their linked blog post.
There’s also:
- this post (uses milled HDPE plates)
- this post (machined + anodised aluminium)
- this might count? (uses gripper to actuate a water sampler)
Note the gripper mechanical properties, and drawings and 3D models we provide in the technical details tab of the gripper product page, which will be useful for designing custom jaws or an extension to the existing ones