A design we've had success with for a "harvester" is to use "fingers":
- drill hole along shaft normal to axis
- press fit or glue flexible extension springs into the holes
- push soft latex tubing over springs
You can adjust the length and stiffness of the spring, and length of rubber "fingers" to achieve varying performance. We used this to collect the wiffle balls last year. It's like what a lot of team do with zip ties, but the rubber grabs much better.