There are a couple different resins that I've used... not sure where
you are but the ones I've tried are readily available in the US
The first is Envirotex Lite, which is probably too soft for your
applications. It's a resiliant resin that's used for bar tops, and
mixed in a 1-1 ratio of resin to hardener. I'm pretty sure it's too
soft to polish, but it does have the advantage of being fairly
The second is Castin' Craft, which is much more viscous than
envirotex lite and uses a few drops of catalyst per ounce of resin.
It's much harder, and does best with objects that are at least 1/4
inch thick. I believe castin' craft can be polished, but you might
want to practice first.
http://www.smooth-on.com/ also sells a number of pourable plastics
in many configurations and colors, I'd check there too.