I've had professional molds before, and these work just as well. They're not as durable, and likely not as attractive, but they're pretty good for $15 and beat the crap out of 3 sets of foamies for durability. Frankly, I think they're brilliant.
I used the Radians kit from sportsman's warehouse.
Safety note: The compound is a 2 part silicone epoxy that hardens when mixed. As a test, separate a tiny part or both compounds, mix together and set aside for 10 minutes. If it hardens, you know that the chemicals are still good. It it doesn't harden, return the kit and exchange for another. this ensures that it doesn't fail to cure in your ear and leave gooey silicone in your ear canal.
Separate the mix halves into 2 portions. Take 1 portion of each half and knead together. until it is one uniform color. Press into your ear per the directions. You want it to get into the canal maybe 1/2 inch. Don't be an idiot and press it into your eardrum. You'll just have to trim that bit off anyway.
Then press the IEM into the soft compound in your ear. When it's in, it should be in more or less the same depth that it would be in if you were using regular ear tips.
Let it sit for 10 minutes. Do not talk or chew as that will deform the mold. After 10-15 minutes, carefully grasp the outside of the mold and extract with a pulling-twisting motion.
At that Point, I trimmed the bit that went into the ear canal until it was close to the end of the IEM, removed the IEM and then completed the hole allowing the IEM transducer to fire into the ear unobstructed.
Repeat with the other ear.
Let the molds cure for 3 hours, after which you can trim excess material off and make them more pleasing looking.
