Howdy, long time lurker, very rare poster. Thanks to such a great community of enthusiasts!
I recently took a stab at making my own IEM tips, using silicone putty, and I'd call the initial results a success :)
I was recently reading about some IEM's which feature custom tips made from ear impressions and suddenly I felt the DIY urge coming on strong.
A few googles later and I discovered that not only was this possible, but it was popular enough to have been covered on the MAKE blog:
Don't do any of this unless you are A) crazy, and B) crazy. You could end up in the emergency room explaining the importance of a good seal for proper bass response to the aural surgeon as he surgically removes silicone from your ears. DON'T GROW UP TO BE LIKE ME, KIDS!
The silicone putty:
I ran down to Michael's craft supply and picked up some silicone putty for mold making ($20):
It turns out this is a ton of putty. Having made two sets of tips, I'm sure I could get a dozen set of tips out of this much putty.
The ("disposable") IEM's:
I then went to target and picked up a set of the cheapest IEM's I could find, the Sony EX10LP's ($15, but on sale for $12!):
If you decide to toy around with this yourself, I'd highly advise starting with "disposable" ear buds like this. I nicked the cord with a razor blade while trimming up the silicone, and I'm on my second attempt (probably have several more to go) of making molds for these buds (it's more difficult that you think to get the position just right).
Working with the silicone putty:
I'd advise making a trial run of working with the putty before putting any in your ear. I grabbed a stop watch and two balls of putty, and got a feel for kneading the putty and how long it took to get it well mixed (about 45 seconds). A technique which seems to work well is to squish the putty flat, then fold it over, and repeat (just like making a katana :).
I molded some putty around a plastic speaker wire binding post I had lying around, just so I'd have a feel for how hard it is to get the putty off of something after it cures (it's pretty easy).
First, clean your ears:
You might think I suggest this in order to avoid screwing up your silicone tips with ear gunk. That's part of it, but the more important part of this is to get a "feel" of how deep your ear canals are, and finding out where your personal comfort level / danger zone is for sticking things in your ear.
I took a Q-tip dipped in alcohol and CAREFULLY, SLOWLY, WITH THE HEEL OF MY HAND BRACED AGAINST MY JAW / FACE, inserted the Q-tip into my ear canal. You'll feel the bend in your ear canal, and beyond that, if you are like me, you'll quickly reach a point where things become uncomfortable and sensitive. I didn't make it as far as my ear drum before I got the heeby jeebies and pulled the Q-tip back out. But more importantly, I now had a visceral feel for exactly where the "Do Not Enter" sign hung in my ear canal.
Practice: just take an impression of your ears:
Next, I mixed up some more silicone putty and stuck it in my ears. I err'ed on the side of using too much, so that I'd be able to have some practice later with trimming the impression with a razor blade and seeing what parts of the impression were important / superfluous. If you pay close attention, you'll be able to vaguely feel how far the putty is being pushed into your ear canal.
Right at about the 4 minute mark (you remembered to start your stop watch, didn't you? :), the snap-crackle-pop orchestra started in my ear (that's the silicone reacting and taking a permanent shape). I could also feel the putty get a little warm (it's an exothermic reaction). That will go on for quite a while, but after about the 8 minute mark, I could feel the putty had already taken a permanent shape.
I very carefully and slowly rotated and pulled the impression out of my ear. Take your time and be careful here, as this impression is the one which you are most likely to have made a mistake and pushed the putty in too far, and you also have the least amount of experience with how much force it takes to tear the putty, and what's the best technique for extracting the impression from your ear canal. If in doubt, wiggle and twist until you feel confident that the impression isn't sticking to your skin, then twist and pull it out. Don't fight it.
For reals: make the IEM tips:
I've made two sets of tip at this point (which, with the practice impressions, makes three attempts), and what worked well for me was:
* I didn't need as much putty as I would have thought.
* Before making the tips, take the existing silicone tips off of your ear buds and stick your ear buds in your ears. Get a good feel for where you want them to be, because that's exactly how you'll have to position them when making the impressions (by feel).
* You want the sound hole of your ear buds positioned so that they are pointing directly down your ear canal. This will give you the best shot at being able to trim the silicone away in such a way that you don't block the sound (on my first go-round, I ended up having to drill a passage way through the silicone, with didn't work out very well. You want to be able to just carve out a cone with a razor blade and be done with it).
I made the impressions one at a time (about 8 minutes each), and by 16 minutes into the process, I was able to start trimming up the first impression with a razor blade (DON'T DO THIS WITH THE IMPRESSIONS STILL IN YOUR EAR!).
Never before have I had so much fun listening to headphones which sound terrible!
My second result was very promising, and now I think I've got a good feel for exactly where I need to position the ear buds for the next attempt (as of my second attempt, the sound hole of the ear buds is too close to being squished up against the side of my ear canal, and so muffles the sound in one ear).
After another attempt with the $12 ear buds, I think I'll feel confident with trying this on some more expensive IEM's.
Variations I'd like to explore:
Insta-putty makes moldable silicone ear plugs (though I believe you are limited in reshaping them because the silicone has already been mixed and set), but they appear to have a more sticky / gooey formulation of silicone, which I imagine would make a more reliable seal. If I can find a more gooey formulation of mixable silicone putty, I'll definitely take a crack at that: