if we make them,say 48 x 8 x 4,7mm it´d fit any backing with sanding material off,always better than a pad thats too small lol
the middle cutout is 11mm,if we make it 10 its cuttable to 11(power pad backings)and fitting to echo,tnn and so on.
i played mindgames of getting some modelling clay and press the refill into it to make a negative,then bake it to harden it.
the 3d printed version would be more pimped though...