1. 3D printer:
Any fused deposition printer will work. You will NOT
be modifying this printer, so don't be afraid of ruining it. Also, you'll need a reel of PLA. - ABS might work, but it's higher melt temperature makes it more difficult to keep fluid.
2. RTV Rubber: Room Temperature Vulcanizing Rubber
is one of the most popular mold making materials available. It's a stretchable rubber that can be fast curing, forgiving about undercuts and readily available. You'll also need the catalyst to cure it, a rubber to rubber mold release, mixing sticks, mixing container and a brush. I get my RTV materials here
. You can also pick up good quality polymer clay here as well.
Assorted knives to cut, clean and sometimes separate the mold halves will come in handy.
I use plastic blocks to build small RTV molds and make my sprews from those, but a short piece of 1/4" dia. wooden dowel will do just as well.
5. Modeling Clay:
You can use clay made specifically for mold making, or the clay your kids use at school. Both will work, but The better the quality clay you use, the better your results will be and the easier time you'll have.
6. Something to make a mold with:
For this application, you'll need a ceramic container to make your molds in. A few years ago, I picked up several boxes of Ikea candle holders for $4.04. At the time, I hadn't a clue as to what they were, but knew I'd be able to use them someday. I was right. If you can find these, it's like they were custom made for the job... More on that later.
If you can't find them, a ceramic demitasse cup should work. Be creative.
7. Something to make a mold of:
Any small object you'd like to duplicate. Keep it small... Money is a no-no.
8. Silicone Lubricant:
If you want your molds to last longer, silicone lubricant will help.
: RTV takes hours to cure.. And you'll need to cure things twice. There's also a high chance of an "iffy" result. Depending on the quality of your mold, the item you choose, the length of time for the extrusion, the temperature and the equipment doing the work.
Excellent results are possible, but patience is an absolute requirement.