People always ask which supplies are the best to use when working on this stuff, so I will tell you what I have personally used.
I have used Smoothcast 300 resin. It has an easy 1:1 mixing ratio, cures pretty fast, and comes out in a nice clean white color. It sands nicely, and is just an overall good product.
I have also used Oomoo 30 molding silicon. So far I have noticed that it is very easy to mix, very easy to pour, and sets within a reasonable time though I usually let all silicon and resin sit 24 hours. I have noticed though that small pieces have come off after pouring a fresh piece. It tends to stick in small crevices, moreso than I have noticed with other products.
I have used their quickset molding silicon and it does very well with small props. It's harder to mix though, it is a 10:1 mixing ratio.
Their Fixit Sculpt is fantastic, and I use it instead of autobody filler any chance I get. It has a clay like consistency which is great for small repairs or larger detail work. It has about a four hour working time as well.