Working on the wideners now, my first idea was a bit of a fail, it worked in my head, but not in reality!
Then I had a better Idea! so this is 20mm thick
attach the regular hub to the extender (need more screws!)
Then attach to the axle with the nut
Then made this little bit to hold the new stub axle bolt
and push into the hole
drilled and taped 2 holes nearly the whole width of the widener
and lock in place with two 25mm grub screws, its solid and spins true. Just need to order some more delrin bar as I used mine up making wideners that dont work!