So it's a spacer inside with a solid cover slipped over, or one piece?
I believe for the non ABS bikes, they are one piece solid material (may be hollow to clear the screws for the rotors). Just like the MOCO's chrome spacer, just larger to cover the rotor screws.
If he is able to do for the ABS bikes for the sensor, it would have to be a shell to cover the sensor and the wire to poke thru as the ABS sensor is actually the spacer on the LH side.
He already has a spacer for the LH side for ABS, just not the ABS sensor side.