Ordinarily I wouldn't post something like this, and certainly wouldn't edit the title to include words like "insanely", but if you have ever made cast resin par

Ordinarily I wouldn't post something like this, and certainly wouldn't edit the title to include words like "insanely", but if you have ever made cast resin parts you would know just how bonkers this is. TL/DR: I am in awe. Even just from the detail I can see in the video I'm not sure how they managed to make the master parts they cast the molds off of. I suspect the original parts they're duplicating may actually be machined from metal, because the problem Adam points out that silicone molds deteriorate when used to make castings exists for making the molds off of original (or master) parts as well (though to a lesser degree). And if your master part falls apart from handling while pulling it out of the mold, you're potentially screwed: it might not be repairable, you have to make another identical master part first. So at the very least you have to either minimize the mold-making failures, and your run of the mill vibration table and vacuum chamber aren't going to cut it as every bubble in the silicone that sticks to the original part is going to produce defects in the cast pieces, you have to be a master at mixing the silicone without introducing air bubbles in the first place (maybe even mixing it in a vacuum), or option 2 is your original master parts have to be really durable with no potential weak spots so you can afford to discard failed molds. I mean, I made master parts, molds, and cast duplicate parts professionally for a while, and I never even attempted anything as ambitious as this. My brain is tying itself into knots imagining how to get this done. Whoever made this probably invented entirely new techniques along the way, because they certainly didn't cut any corners. Edited to add: one way to get this done if price was no object is not to necessarily have an original part per-se at all, but to treat making the silicone molds as if you were making injection molded plastic parts, so the "original" is actually two sets of metal molds that each only has one positive surface. Each metal mold set produces one of the two silicon mold halves that is perfectly registered to fit the other. Voila, an unlimited supply of perfect silicone molds with no danger of damaging an original master part. A bonus would be that details like pour and exit channels can be made arbitrarily without introducing more problems except for increasing the cost of the metal master molds. I'm not convinced that's what they did though, because the expense is prohibitive, but it would explain why they would be willing to discard the silicone molds after using them for only twelve times. Edited again to add: If you're machining mold sets to produce the silicone mold halves, there may not be any need to machine them from metal. Plastic might do, since the curing silicone doesn't get particularly hot (unlike the resin that gets poured into the silicone to make the final parts). That would reduce the cost considerably.