Big sanding block with comfortable handle for the prof.
To create it in addition you will need:
1 M4x30 screw (M4x25 may be also good)
1 M4 nut
First remove built in supports from the "roller" - to do this use hands and big radius drill:
After this fix M4 screw and nut.
Enter screw inside the roller and set nut on it - this will help you to fix nut more easy.
When nut will be ready we can start to fix screw.
Put it inside the body:
Here you have to use epoxy glue or something similar to fix screw hard. (I used material that start to be like steel after drying.)
After this close stopper with nut and give model to get there forms in correct directions