I am thinking about making some Dividing plates,would there be any interest in these.

They could either be the standard size or holes could be made to suit.

The standards diameter is 3," plates could extend to roughly 3 1'2" and still clear the steady clamp , if a larger plate was used you would need to increase the length of the sector arms,not a big job you would still retain the originals with etensions attached to the arm to accomadate a larger OD.