Looking for help on casting small parts

[twilight]

Ok, here's an update on how I progressed with making a mold and casting parts.

Here is what I ended up purchasing and like dave1905 it is very flexible.


Here are the hopper latches in the mold box. Yes they are LEGO's, I read about using them years ago and have used them since. But my daughter gets mad at me when I use them(she thinks they're hers, but they are from my private stash).


And set to cure for 18 hours.


But, what happened is two of the masters floated when I poured the mold material in(unknown to me ), making two of the molds unusable. But making the most of a bad situation I was able to use the good molds to make 2 castings. And I added them to the original 4. I need 6 latches for each hopper I'm working on. I have four hoppers total. Another 18 hours of cure time, here's where I got to. The grayer looking castings are the castings I made.



When I laid the masters out again I CA'd them to a piece of stage glass from an old overhead projector instead of using double sided tape like I did on the first mold.

Here's how they came out right off the mold. When I poured the casting resin on the mold I used a popsicle stick to push resin into the mold, breaking surface tension and releasing air bubbles. Also mentioned in the directions of the mold material is to brush the mold surface with talc or baby powder to release surface tension which I did. I also used mold release. Also, when the castings came off the mold they were a little soft. So, I stuck them in the toaster oven at 200 deg for like 3 minutes. Which really harden them up.


And finally with a coat of primer.


Thanks everyone for your suggestions. I'm very happy how these turned out. I've made 24 of them already, enough to do 4 hoppers.