This is a project from my archives but i think it really shows good, simple process to make a significant amount of a thing.
I was contracted to make a 500 piece batch of small plastic toys. The design was a simple extrusion of an existing company logo.
I ran through the possible processes to do it, the volume needed was too high to use just a 3-d printing solution and too small to justify the cost of traditional manufacturing.
Step 1: Basic geometry
Once we had the scale decided i used a high res 3-d printer to print a test mold which was a simple negative cavity made from the original 3-d file. I used this just to prove the process and make sure the geometry of the part wouldn't cause any casting problems and to check that the final cast part would be durable enough.
Step 2: Making the master
You can use any method you are comfortable with to get to this point; cut, carve, print, sculpt, spit, whatever the important thing to remember for this project is it was going to be a simple 1 sided mold. All of my geometry needed to rise from a single ground plane.
Basically i wanted to make slightly complex ice-cubes.
Step 3: Make a mold
I used smooth-on oomoo silicone to make the molds since the part was so simple and this particular silicone is incredibly easy to use. the final parts were cast with smooth-on smooth cast 300 and 325 with compatible pigments.
Step 4: Get to work
the reason for adding extra is so any bubbles in the mixture would rise out of the mold in to the overflow above the top edge of the casting. I then ran a squeegee over the top of the overflowing molds and forced all the excess in to channels that i designed in to the mold. You could just push the excess over the edge of the mold but i like to make a slight attempt to keep my work area clean.
This small detail is incredibly helpful in that you virtually eliminate any finish work. The open side of the piece will now be bubble free and shouldn't have much if any flash to clean up. The part comes out of the mold and goes right in to packaging without
having to spend unnecessary time and energy sanding and buffing.
once the resin was set, in this case a few minutes, you just pop the parts out just like an ice cube tray.