Okay, hi everyone, I was hoping I could get some help? I want to use 3d printed items to make a mould as I sell pewter keyrings. They are quite small and are detailed. The 3d printed item needs to withstand heat and look good enough to produce a mould of. I was wondering, what do I need to know, what are some good printers that are cheap yet reliable and is there anything I should be looking out for? Thank you!
People do not tend to directly print molds for molding molten metals with any printer under $2000 as far as I know. They use techniques like lost PLA molding where the print displaces sand or something else and then the molten metal is poured on it, melts/burns the plastic away and fills in the remaining cavity.
Printing a prototype piece of jewelry and then using something like https://www.amazon.com/18854-Stove-Fireplace-Mortar-10-Ounce/dp/B0006MXS4C might work to get you a mold to directly pour molten metal in. I have not tried myself. Nor have I done lost PLA molding myself. Grit in the mold would effect the detail. Hard setting materiels like mortar might not make it easy to release the pewter from the mold without breaking it.
This article is worth a read if you want to do something like lost PLA/ABS molding. http://makezine.com/projects/guide-to-3d-printing-2014/metal-casting-with-your-3d-printer/
This should be useful if you want to print a medallion and use casting sand imprints of the printed medallion as your mold. For clarity, the casting sand is the mold. https://www.youtube.com/watch?v=bk8ADidAjvg
In this case you would probably want to get it SLA/DLP printed and then create a negative mold. Don’t think any plastic would withstand the heat
CNC milling a mold in plaster might actually make more sense, I think. Mix some plaster into a block, clamp it down, mill out the pattern, pour molten pewter into the pattern, done.
Print a positive. Use plaster of paris/play sand to make a mold. Use the plaster of paris/play sand mold.
@ThantiK : I’ve wondered, why the playsand additive? I’ve heard other people mention it as well, but wasn’t sure of the purpose? I’ve see folks use just plain plaster with no sand and it seemed to work too, so I’m trying to figure out the pro\cons of it.
There is play sand you can get where you simply press your master item on, remove the master and pour in molten metal. There is no waiting for a mold to set or bake. Of course you should have the play sand in a container. It will turn to dust till at least the point where it has cooled off. I can provide a YouTube video.
I do greensand casting that uses sand with a clay binder, I have a hard time understanding how just regular play sand would hold its form when the positive is removed. But I’m no expert, just based on experience. I’m mainly just interested in the roll sand plays with the plaster.
https://youtu.be/L3t-jBATM0w should suffice.
AH, mutant blue sand, it makes sense now 
I have other videos marked for how to make the stuff. Some of the videos that I had marked before mut have been deleted or something. Perhaps the author of the other videos did not have a proper container for his mold and had a fire.
Send it to Materialise