you know you can adjust up to at least 5mm z-height just by using the adjuster knobs ?
ie: you simply don't need shims unless you're adding something really thick.

Amazing how many people do things like that when it's not actually necessary.

As far filament holding the best I've found is this one: https://www.thingiverse.com/thing:430453
I use it with 8mm diameter carriage bolts. I wrap some plumbers tape around the pointy end which also stops the reel sliding off.
I've got filament spools with all sorts of different diameter holes. Everything from 10mm (flexismart 200gm roll), all taulman spools are around 12mm, on up to ones big enough to put my arm through. So the standard 30mm diameter shaft is pretty much useless.
The long thin metal bolts work a lot better.

On my delta I use an angled spoolholder which prevents filament tangling round the spool holder, and uses gravity to hold the spool against the machine. Would be pretty easy to make one for the replicator clone machines.