Making a Custom In-ear Monitor




Introduction: Making a Custom In-ear Monitor

About: Check out my youtube channel:

Instead of spending $500 - $1000++ on brand name Custom IEMs, I've decided to embark upon a journey to creating my own Custom IEMs.
It's probably going to result in many failures and in the end the cost savings may not even be worth it anymore, but at least it'll be a fun learning experience as well as satisfying for my inner DIY fanatic.

1) Prototype Epoxy IEMs, using universal IEM as driver.----------[DONE]
2) Explore making moulds and eventually cast a resin cast.--- [DONE]
3) Prototype Resin IEMs, using universal IEM as driver.--------- [DONE]
4) Explore creating own driver setup. --------------------------------- [Nil]
5) Resin IEMs, using DIY drivers. -------------------------------------  [Nil]

Thats my plan, tentatively of course :)

I plan to build upon this instructable until I reach the final goal.

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Step 1: Stage 1: Materials

- Epoxy putty (Not the steel variety)
- Vaseline
- Any cheap dremel or drill (Epoxy isn't that hard to drill, I think...)
- A cheap pair of universal IEMs

Optional Materials:
- Acrylic Paint (I used nail polish, would not recommend it for the fact that it worries me to put the result into my ears -.-)
- Clear coat spray paint
- Hot glue for securing IEM to Epoxy shells (I used some gummy yellow shoe repair glue thingy)

Step 2: Stage 1: Making Your Own Ear Impressions

Closed or Open Impressions
First of all, you can take impressions either with your mouth open or closed.
I would recommend open mouthed, biting on a mint tin or something while taking the impressions, read below for more views on the issue.

1) I used epoxy putty but I'm sure any material that is pliable and hardens when cured will do the job. In fact, Epoxy putty is a pretty poor choice as people are known to be allergic to epoxy. Therefore, if you decide to use epoxy as I did, do not wear a glove while mixing, if you're allergic, it's better to find out with your fingers not your ear canal.
2) Some people have "hooked canals", so if the impression material you're using is not flexible, you may have a really hard time removing it. Epoxy is not flexible when cured.

Getting down to making the impressions
1) Lube up your inner ears and the outer ears with vaseline, strangely, it's the outer part that sticks more to the epoxy, so lube up well to avoid PAIN.
2) Mix up the epoxy, you'll need about a quarter stick of it for each ear. (Taking reference from Selley's Epoxy putty sticks) Wet your fingers and palms to prevent sticking and try to make it as smooth a ball as possible, you don't want any large folds or gaps as it'll show in the final product. Also you can choose to do either one of the ears first or both.
3) Insert bite block now.
4) Push the ball against your ears and push it in, smoothing and folding the excess on the sides.
(See video for better explanation, )

5) Watch, Read or do something utterly boring for around 30-45 minutes. (Trust me, you do not want to smile or frown or worse laugh, it changes the shape and size of your ear canal, try not to swallow too)
6) Pull your ear outward and backwards and slowly nudge the impressions out, expect some mild pain from the outer ear but it's nothing unbearable, like removing a band-aid that got too sticky.
7) Let your impressions cure for a further 4 - 5 hours before trying to work with them.

Other Notes
1) I've tried dyeing the epoxy during mixing with food dye. Forget it, epoxy doesn't accept food dye well at all, see pictures. The impressions only change colour mildly. Maybe if you had some powder pigment, I would assume it will work much better.

Step 3: Stage 1: Working the Impressions

Okay, there are a couple of things you want to do with the impressions after they have cured.
I apologise for the lack of photos for these parts, wasn't thinking of documenting the process when I was actually doing it.

There will be 2 holes made for this part, the sound bore and the larger one made to fit the universal IEM of your choice.

I drilled my sound bore 4mm in diameter and halfway into the material starting from the ear tip.
The width of the bore depends on how wide your ear canals are, aim for a moderate size, too small and the sound will be slightly diminished, too large and it'll be a earwax dumping ground.

Next, I drilled another 4mm hole from the back of the impression to connect to the sound bore, you'll have to plan the direction and depth with which to drill in order to connect these 2 holes.
I won't lie, I've destroyed one perfectly good pair of impressions due to bad drilling, but they became my test painting palette so it was fine.

After your holes connect, measure the nozzle width and depth of your universal IEM and widen the back hole accordingly, test fit the universal IEMs and if you get a snug fit, we're good.
Otherwise, it's fine for it to be a little loose, we'll just hot glue them in afterwards.

Cleaning up
First of all, wash the impressions with soap to get rid of the Vaseline and waste material from the drilling, if you're planning on painting the impressions, this ensures your paint wall adhere well.
Depending on how much Vaseline you used, its probably not going to be squeaky clean with just one wash.

Make sure the impression is clean and dry before painting.
Paint your impressions with either acrylic paint or spray paint and finish with a few layers of clear coat to seal it all in.
Remember to stuff the holes with tissue beforehand to prevent the paint from clogging up the holes.
Don't use too many layers of paint though, each layer adds to the thickness of the material, a moderate amount would make the plugs more snugly fitting but too much will make them too big, and thick layers of acrylic paint have the tendency to get easily peeled or gouged...

Step 4: Stage 1: Finishing Up!

The end is nigh!!

Attach Universal IEM
Once your happy with the plugs.
Coat the nozzle of your Universal IEM with some glue and insert them into the plugs, when the glue sets, we're DONE!

Test Drive
Take it out for a spin and note for sound leakage where plug connects to IEMs, apply more hot glue around the edges of the connection to seal it up if there's any leakage.

After Action Review
Okay, my honest opinion of these custom IEMs are that the sound is pretty much the same as the universal IEMs I put into them, none of that improved highs/ mids/ lows nonsense, I suspect that is only achievable when I start building my own driver setups. (A long way to go)
I would of course aim to use a much better Universal IEM at later stages (Stage 3); maybe my SoundMagic PL50s or a Klipsh...
The customs do feel more comfortable however, at the trade-off cost of looking slightly ridiculous (largely due to berry colours) and bulkier.
Isolation improved but it's still not the complete silence I was expecting.

And with this, I can say:
and publish this Instructable!

I will keep updating this as my plan progresses, I promise to take more photos in the future :)

Step 5: Stage 2: Thoughts...

1) Prototype Epoxy IEMs, using universal IEM as driver.----------[DONE]
2) Explore making moulds and eventually cast a resin cast.--- [In-Progress]
3) Prototype Resin IEMs, using universal IEM as driver.--------- [Nil]
4) Explore creating own driver setup. --------------------------------- [Nil]
5) Resin IEMs, using DIY drivers.  ------------------------------------- [Nil]

I have been researching into mould and cast making, and it seems like the best commercially available way is to use RTV silicone for the mould and some kind of casting resin for the cast.
E.g.  or
See also: «Very Useful Link For Information Pertaining To Casting Resins»

However, these do not come cheap, so I'll be looking for alternative ways to make a mould...
It has to be a flexible material though, as the ear impressions are not exactly mould-friendly shaped...
Currently considering using OOGOO, credit to Creator of OOGOO   and Guy Who Gave me Idea of using OOGOO for Mould

Stay tuned...

Step 6: Stage 2: Materials

Materials to make mould
- Make a pair of impressions
- A suitable container to hold the mold
- Vaseline

Materials to make cast
- Some sort of clear 2 part resin.

I used locally available ones but any resin will do fine, key points to look out for are:
- Minimal Shrinkage (If it shrinks, it's not a perfect fit, DUH)
- Compatibility with silicone molds (Very likely, silicone molds stick to very few materials)
- Can it be dyed? (For those who want to make coloured shells. I DO!)
- Price (There are premium resins around with unique qualities such as being flame retardant and non-reactive stain proof finish, we don't need these qualities unless you're a audiophillic fireman who specialises in stains & dye factory fires, the extra cost is just not worth it)
- Ease of flow (To ensure that it gets into every nook and cranny of the mold)

Materials to make OOGOO
- Silicone caulking, acetic cure
- Cornstarch (I used Sweet Potato Starch)
- Mineral Spirit (I used Lighter Fluid)
- A pair of sandals (This smells way too awful to be carried out in the confines of your home)
- Gloves (Optional, safety first)
- Follow this Instructable to make the OOGOO

*See Pictures for important tip on making impressions, don't push the material in too deep.
It hurts and the extra length is worthless anyway, I had to file it down to size...

Step 7: Stage 2: OOGOO FAIL

Okay, I have just failed majorly...

After lubing up my impressions, I went to mix up some OOGOO, used a container that was way too big and the OOGOO solidified before I was able to get it to a acceptable consistency for my purposes.

Since I've wasted almost all the silicone caulking which was not of the translucent variety by the way *Sob*
I should give it another shot but using the rejected left ear impression that was too short, just in case I screw up the 2 good ones.
If I should fail again, I might have to give in and go buy some Silicone RTV which costs $80 a kg here.

So the main learning point here is, don't mix too much OOGOO at a time, unless you have some sort of mixing device, or it'll just solidify on you.
Mixing a large batch seems pretty redundant too, considering that fresh OOGOO adheres well even to cured OOGOO.
Mmmm, food for thought *DROOL...* 

After feeling the end product of OOGOO, I also realised that it is not a suitable material for making the actual Custom IEM shells as it is too flexible. It is however firm and rubbery so it would have made an excellent mould (I think...)

Step 8: Stage 2: OOGOO Success?

I mixed up the OOGOO in a small plastic cylindrical container, and stuck the impression into the OOGOO once it was "smooth"
I was not expecting good results due to the OOGOO being full of air bubbles (Need advise on this, how do I avoid those bubbles?)

The results were very surprising,
1) The OOGOO released from the impressions as well as the container even though I neglected to coat either one with Vaseline.
2) I was not convinced that the mould would be accurate due to worries about the air bubbles, so I filled it with water and froze it. The ice cast came out looking more or less identical to the original impression. However I account this as a fluke as I do not know how to mix OOGOO up without creating large pockets of air in the material.

Other notes
- I believe I received mild acid burns from the silicone caulking, probably due to the acetic acid, so take care and use gloves or just avoid poking it with your bare fingers.
- I will not be making molds for the main impressions yet, until I can mix up OOGOO without the bubbles.
- Will also be busy hunting for a suitable casting resin.

Stay tuned...
And give suggestions on how to mix OOGOO properly, thanks :)

[Update 270611]
It is insanely hard to find materials here in Singapore, but I found a few suppliers of casting resin. (For the benefit of those in Singapore: LINK & LINK )
Yeah, wondering if I should just buy some silicone RTV for the moulds too, but that would be costly...
My OOGOO mould has shrunk dramatically, it's now 80% of it's original diameter, that sucks...

Oh, just received a PRO membership, SWEET, now I can underline my sub-headers!!!!

Step 9: Stage 2: Proper Materials & Results

- Silicone RTV
- Polyester Resin

Like any lazy person, I've decided to throw money at the mould and cast problem and purchased some silicone RTV and polyester resin from a local chemical distributor.

See below for instructions on making moulds with Silicone RTV and casting with silicone moulds.

Making the Mould.


- The polyester resin will cure with a bumpy tacky surface for the parts in contact with the silicone due to 2 reasons.
  1. Firstly, the silicone mould is cold when resin is poured in.
  2. Secondly, silicone by nature conducts heat away too quickly from the catalysed  resin.
  3. This causes incomplete curing as the exothermic reaction due to the catalyst is necessary to cure the resin.
- I've managed to get past this problem by first heating the mould up with my oven @ 70 degrees celsius and by allowing the resin to cure while the mould was placed in a pre heated oven.

Step 10: Stage 3: Prototype Resin IEMs, Using Universal IEM As Driver.

Well, it's been awhile since I've updated this instructable.

Actually finished my customs LONG ago, like 2 days after I published step 9, just never got to updating this.

So yea, the pictures are pretty self explanatory.

The final product is functional, fits well, isolates quite a bit of noise. However, the driver used was a sub-par, dynamic driver from a mid-range Audio-technica earphone(same ones used in step 4). As a result, the sound quality is up to what I had originally wanted.

The plan is to now create my own balanced armature setup and embed it into another pair of customs, however, I am no longer enthusiastic about this project. Between leaving the army, finding jobs, and finalising my university admission paperwork, this project just fell further and further into the background for me.

I guess my custom IEM adventure ends here, it's been fun.

Thanks to those who followed and commented on this instructable.

Side notes:
-Meeknok has a really good idea for using Oogoo to make customs. It's kinda like a hassle free 2 stage process, no tools required. I like it, do check it out.

-My new obsession is now coffee.
Roasting, cupping, grinding, brewing...
It fills a gap that being an audiophile just doesn't, i.e. it's EDIBLE.

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25 Discussions


8 years ago on Introduction

any type of glue i can use that wont irritate the skin around my ears? Wedding DJ Melbourne Im thinking of using these inside my headphones when i DJ


Reply 1 year ago

How about silicon glue? The kind used to seal aquariums? It is made of hypo allergenic material.


1 year ago on Step 5

Why not use agar or gelitin?


4 years ago


5 years ago on Introduction

what's the most skin safe/non-toxic material for making the actual plugs?


6 years ago on Step 10

hey! how did you get the actual earphones inside the polyester resin model?

I'm kinda doing the same thing for my project right now and desperately need help. Much appreciated!


Reply 6 years ago on Introduction

I opened a cavity just large enough to fit the earphone drivers, angle the driver towards the sound hole and fix in place with some rubbery adhesive, I used shoe repair gum.

Put a knot into the wire to prevent it from pulling at the soldered connection to the driver, shove the knot into the cavity and fill up with more resin.

Fill with less resin so that it cures with a concave indent, this allows you to add artwork. Use soluble inks dissolved in abit of resin to add a translucent colour layer.

Or acrylic paints to draw a picture then fill up with resin to fix the artwork.


8 years ago on Step 9

Great stuff; I can offer a few hints and a caution or two. First, a caution: when pressing stuff in your ears, use a stop. A stop is a small bit of foam or cotton that has a thread threaded through it and dangling outside your ear. This will keep you from inadvertently bonding something to your eardrum and yanking it out with the mold. Maybe. I recommend finding someone to make your impressions for you - I found that I could get a local audiologist to do mine professionally for $40 total ($20/side).

Now - I've been going down the same road you are in various ways. I've discovered something you may find useful: Search youtube for Ultimate Ears, and watch their factory process. They make a mold from your impression, then cast an intermediate positive, which they "clean up" and polish. Then they dip it in some sort of wax or polymer that adds a thickened, shiny smooth layer. THEN they make the final mold. This step seems to be crucial in achieving the isolation you're (we're) looking for.

When you go to make your own drivers, check the Knowles GQ series of drivers. It's a dual -driver balanced armature; I'd almost bet money it's what's in Apple's BA in-ear. I'm working on re-molding my Apple in-ear (balanced armature ones) into a custom IEM. I'll report back when I'm done. if it works well, it gets you a $250-600 set of IEMS (dual balanced armature) for $70 and some materials - and a lot of fun. :)


Oogoo actually works quite well for the IEM material in my experience. Before you had tried the Oogoo for the mold, I saw this 'ible and was inspired by my lack of epoxy resin to make it from Oogoo. I put small pieces of a plastic drinking straw on my pair of Skullcandy earbuds instead of the rubber tips, cut them to length to make a sound tunnel, encased each earbud in a large blob of Oogoo and squished it into my ear until it was cured. Remove the straw (Oogoo won't stick to polycarbonate or polyethylene plastics, including straws, plastic bags, and most cheap earbud bodies) and there you are. They sound much sharper overall, bass is better, sound isolation is excellent, and they feel wonderful - very little ear fatigue after wearing them for hours.

See if you can find the really cheap, clear silicone caulk rather than the opaque stuff; it seems to be thinner and easier to work with, and you can color it with acrylic paint. Putting less cornstarch in will make it take longer to cure, allowing you more working time with the Oogoo, but it will still cure all the way through if mixed thoroughly.

Also, I may try your method of making a cast of my ear and then making a mold from that, but making the cast with Oogoo rather than epoxy (doesn't rip out as many ear hairs...). With the direct approach I used, it was difficult to get the earbuds placed right, but I suspect that would be remedied with the external-mold approach.

I should note that the Oogoo stung a bit while it was in my ears, but it really wasn't bad. It felt like having hot water in my ear. The silicone caulk used in Oogoo releases acetic acid as it cures, which is essentially concentrated vinegar, so it's not toxic or anything. It started to feel hot after a couple minutes, but that can be reduced by lubricating one's ear with oil or Vaseline because the acid won't get through the lube as much. I wouldn't recommend doing it often, but you should only have to do it once or twice.

Again, great Instructable - I look forward to seeing your continued progress!

daemon ulf
daemon ulf

8 years ago on Introduction

wouldst kids clay work, Good Sir? or dost thou think latex of some kind, wouldst work, or mayhap even rubber caulking wouldst work,, but all-in-all 'tis verily a mighty fine 'ible


Reply 8 years ago on Introduction

Haha, art thou referring to the impression material or the mould material?


8 years ago on Introduction

you can get "mold your own earplug" kits at walgreens. I bought one of those and stuck my skullcandy in-ear headphones into it when i was making the mold. This could easily be used in your project..

heres a kit i found on amazon for $9


8 years ago on Introduction

there's some good diy sugru (or "oogoo") instructables on the site, for the cost of a tube of silicone (~$2 @ walmart). just a thought. Good luck in your Experimentations!

Retro Correct
Retro Correct

Reply 8 years ago on Introduction

You wouldn't want to use oogoo, seeing that it is irritating to human flesh.

Retro Correct
Retro Correct

Reply 8 years ago on Introduction

Perhaps, I'm know expert, but that sounds like a reasonable idea; provided that that will still make oogoo. I believe that oogoo requires a specific sillicon (would someone investigate this furthur? I have little experience with oogoo)


8 years ago on Introduction

i wonder if this could be modified (read: simplified) to create custom fitted earplugs. . . .I've been wanting a pair for when i'm riding my motorcycle to help cut back on wind noise but the commercial ones are outrageously expensive . . .


Reply 8 years ago on Introduction

Hmm, without drilling the holes, these are already custom earplugs, but the epoxy material does not isolate well enough to serve that purpose.

Maybe create a silicone cast version?
Probably should make it slightly thicker than the actual impressions to ensure a tight fit and seal...

It'd be way easier to get those DIY earplug kits from Radians though...


Reply 8 years ago on Introduction

Ha! i guess I haven't searched hard enough! those look perfect, thanks man!