Just glue the brushes of 3 cheap tooth brushes onto the vertical pads with hot glue. (I bought 8 brushes for €2,-).
Fits easily on the two front vertical axis, needs some fiddling to get it on the back vertical axis.
The three brushes will easily go up and down when you move the print bed up and down.
Before and after use I clean the brushes with white spirit. Works excellent!
The author marked this model as their own original creation.