Dear Originator,
There may be many plastics that would meet your requirements. But in terms of highest structural and aesthetic performance, Solvay's Primospire is in my opinion, at this point in time - the ultimate commercially available plastic.
It is however fairly expensive.
http://www.solvayadvancedpolymers.co...808-2-0,00.htm
This material was originally introduced by Mississippi Polymer Technologies as Paramax, and was renamed Primospire after Solvay liked the product so much, they purchased MPT.
Primospire is also available in "stock shapes" from Bodeker Plastics under their tradename Tecamax.
http://www.boedeker.com/tecamax_p.htm
I can personally attest to the fact that it is amazingly machinable! The black Primospire can also be polished to a glass-like finish.
And for the record, other than being a satisfied customer, I have no affiliation with Solvay, MPT, or Bodeker.
Do you have a photo of the parts/resins you have molded thus far?
If you would like more info/input feel free to PM me. I have extensive experience designing plastic parts for both molding and cnc machining.
Good Luck!
Dan