Hi Mat.
You have to cut the Blue plastic grip off the magstick.
This leaves you with a shaft of 10mm wide.
However the shaft that will be screwed into the grip has to be 20mm wide so you need to find a spacer.
I will be using a peice of tube that is 60mm long and 20mm wide. The grip screws need to be screwed through the grip using the supplied holes into the 20mm tube.
If the tube is steel you may need to use a tapper bit to create a hole with screw threads in it.
If the tube is strong plastic then a hole might be enough as the screw will make its own thread in the plastic.
It will be trial and error. It will need to be a strong connection though.
I am still working on how the 10mm shaft will connect into the 20mm tube as my stick is a Pull and Twist stick that can shift from 4-way to 8-way. ( Magstick Plus )
So my grip needs to be able to twist left and right but not pull off when being pulled up.
However this connection can be fused tight if you use the normal Magstick that is switched 4-way/8-way under the control panel. ( white lever ).
I have gotten further with this build and have many pictures to post when i get the chance. I have built a Discs of Tron illuminated deflect button as well. Looks nice.
I have however created this control panel graphic. First attempt. Any input/suggestions/hates/likes welcome.
It looks good on Photo paper and the light colours glow under UV light as does the Tron grip.
The Spinner will be top left and the Tron stick top right in the disc graphic. Track ball in the centre.
( if the image is cut off to the right in your browser then Right click image and View..)

Regards
RIK