This print having the holes lined up with the brush locations gave me an idea that you could 3D print the brush holder to prototype a diy slip ring instead of PCB making. The brushes being glued into the printed base and connected with wires.
This idea allowed by figuring out the right material for said slip ring brushes.
Wonder if anyone learning to CNC could make me some simple copper rings
want
Oh mate! You got me, after seen all work you have done, I think I know what’s gonna be my next project 
oh funny about that idea ,I was going to post yesterday but I forgot.
I had been thinking for a final concept to be a custom composite deck that would act as a spring for the center module.
So the spring issue would be solved by the flex of the deck itself?
no the deck would remain stiff from end to end but there would be a bit sticking out the middle bottom that would compress.
the more I talk about it the more I only see it as being practical as a separate bolted on mechanism to a more traditional deck but never really know until you make the idea come true.
Not sure how to implement it, but air suspension comes to mind, maybe an air tire tube sandwiched between the castor mount and the deck. It would have adjustable pressure and you could use a spring to have retention of the mount to the deck.
A custom air suspension sounds sick, oh what do you think about this idea:
small motor controls the suspension so it can be lifted at will.
Something like a worm drive could raise and lowere the entire unit from above
I would want backdrivability for the suspension aspect, a fairly good reduction and an encoder would be needed possibly but a low reduction and only simple direction and amp limits could work either. Something I would really have to test.
I would use something like a drone motor for this I think, I wonder what a good ESC solution would be… dual VESC I guess haha.
oh it could be a brushed motor
for the gearbox I think just a large printed spur gear slice would work
For the version with a suspension E-caster in the middle a single axle hub could be good for a single sided fork kinda idea.
this one looks nice, and 5.5in in an interesting near AT wheel size
this one is too cute i had to post
And this is all a distraction because regular old springs are an adequate solution for sure.
