Spool bracket rear brace

Added brace to rear of Mistertech's roller system. It eliminates the play/slop from brackets that others stuck shims in for. Posts fit into existing brace holes, and solid design so no worries about posts breaking off like the bracket posts for the bearings had.

Cutout to fit and secure the his filament guide (NON X-max version) if you like to use it. Cut offset from Qidi center tube so you can leave it in.
Also works with the remix filament guide https://www.thingiverse.com/thing:4768618