The molds were still quite soft when I tried this and I didn't mix enough silicone to properly cover the parts so they deformed under their own weight a bit. However the results were pretty decent, the white parts were the printed masters and the green were cast with candle wax.
It's evident on the smaller gear that some air bubbles were caught in the gear teeth. I could probably improve this by brushing the part with mold material first. If I were casting actual parts I would also add patterns for the bolt holes.
I'm not sure that this process is all that practical for actually making useful parts mostly because the molds are not dimensionally stable for more than a day or so. But it does help to get a feel for the process and challenges. These parts are already miles ahead of the previous resin casting I made despite being considerably more detailed. This leads me to believe that it's a good idea to use single-piece, open-topped molds when possible since it allows air to escape. With resin, it should also allow me to poke about in the concavities to dislodge any trapped bubbles.