For the cleaning, you can use fine grade emery papers (white), then
you should use silicone buffs on a micromotor to make the surface
smoother. Once this is done to a satisfactory level, you can use any
of the plastic polishing compounds and use it with micro-motor to
give it almost mirror finish.
However take care that the small prongs and cad pave grains area
should no be polished, as it will not withstand the force. But you
can definitely get a polished shank and underneath.
These resins are hygroscopic will absorb water if after polishing
you use a regular ultrasonic with water to clean the polishing
compound.(For this you can use IPA in ultrasonic unheated)
My experience tell that the most of the resins will break during
mould cutting(based on the intricacy of model). Remember these are
not silver/ brassmodels.
Good luck and let us all know your feedback…