Picture of Clap-Off Bra
The first time I read about Syrian Lingerie I was quite moved. In the West, we often think of Arab cultures as sexually repressed societies, when - in fact - it turns out that they are clearly leaps and bounds ahead of us in advancements in lingerie technology. Those of us in Western cultures have a thing or two to learn from the Syrians about gaudy electronic lingerie.

Henceforth, it became my mission to fast-forward lingerie technology in the West. I figured the first step in this critical mission was to replicate some of the advancements made in Syria. The article of lingerie that resonated most with my inner sensibilities was the clap-off bra. I immediately resolved to make my own clap-off bra as a springboard into Western lingerie innovation.

On a quiet morning, two years ago, I first set out to make a clap off bra in order introduce it to a much more conservative Western audience. After a long arduous process, I am finally proud present to you a reliably working prototype.

As Seen on Kathie Lee on the Today Show and Hoda on the Tonight Show (27 minutes in).

(note: video mildly NSFW)

Step 1: How NOT to make a clap-off bra.

Picture of How NOT to make a clap-off bra.

Before I make anything, I always look for existing devices that already exist that I can model my project after. I knew clap-off bras clearly already existed somewhere (Syria). So, I looked all over the internet for a clap-off bra so I could see how the Syrians made it work. Despite hours of searching, I couldn't find a single instance of one that wasn't poorly 'shopped in 4chan.

This lack of reference annoyed me, but by no means stopped me from my pursuit. My first though was to use a solenoid. This failed. It got too hot. I immediately wrote off all electromagnetic solutions as potential burn hazards. In retrospect, this was a horrible mistake.

My second thought was to build a tiny spring-loaded quick release mechanism. Of course, making a spring-loaded quick release mechanism is a lot easier to speculate about than actually build. This too ended in disaster. I took some time off from the project.

I then partnered with occasional collaborator Noah Weinstein. We discussed various possibilities for opening the bra and finally decided upon exploding the bra off. Unsurprising, the initial test demonstrated that an exploding button in the front of a bra was going to end in disaster. Yet, this did give us another idea.

We finally decided that we were going to get a large metal button, coat it in nitrocellulose and create a brief incendiary event that would burn the thread away. Hence, when the thread burns away, the button would fall off and the bra would open. Fortunately for whatever poor girl who was going to have to wear this, that approach did not work either. No matter what thread we used, we could never get it to fully incinerate and release the button. This disheartened us and the project was laid to rest yet again.

A year or so passed and I decided to try an idea that Noah and I discussed in passing, but never executed upon. The fourth iteration involved pulling the pin out of the center of a hinge, such that by removing the pin, the bra would separate. We initially didn't want to do this because it would involve using a large motor attached to the bra and this didn't seem very 'classy.' Nonetheless, I figured I would give it a go.

I went out and bought the smallest servo motor I could find and on the first attempt to pull out the pin with the motor, I tore the gears apart and the weak little servo was destroyed. As it turns out, pulling out a pin that runs vertically using lateral force is nearly impossible. Once again, I found myself in overly-complicated mechanical quick release territory. I consulted 'ridiculous clothing' expert Rachel McConnell and she surveyed the situation and surmised that my current approach was pretty hopeless. Normally I would just ignore the project for a few more months, but I was hell bent on just finishing the darned thing.

In talking to Rachel about my long list of failures, I recounted the one idea someone suggested to me early on that I had yet to try. Basically, this involved using a small electromagnet and a strong rare earth magnet and polarizing the electromagnet in such a way that it repels the rare earth magnet. Rachel supposed this would work and I supposed I would give it a try.

So, I went to Radioshack to get some magnet wire to wind an electromagnet. They didn't have any. I went to another they didn't have any either. I went to a third, and they too didn't have any. I headed back and had a moment of inspiration. An electromagnet is basically a coil with some metal in the middle. I just needed to find something with a coil. I tore apart my work station looking for a decent-sized coil of any sort, but to no avail. I finally turned to my office-mate - and all-around good guy - Paul Jehlen, and said to him, "Hey, you wouldn't happen to have any solenoids or big relays or anything with a coil in it?" He produced a defective 5V DPDT relay. This was perfect as it is essentially just an electromagnet that controls a switch.

I carefully cut open the DPDT relay, an exposed the coil. I stuck a rare earth magnet to the end and then powered it up and tried to repel it. This didn't work. The magnet was too strong and it would just reposition itself.

Out of sheer curiosity I checked to see how strong the magnet was with a screwdriver that I had lying around. To my amazement, the electromagnet had a fair amount of pull and was able to lift the screwdriver at 5V. I got to thinking, "I wonder what would happen if I gave the 5V coil a full 9V?" So, I did just this an discovered that the coil didn't heat up as much as I had expected it to and the magnet got significantly stronger. It was now apparent to me that the simple electromagnet inside of a relay powered at 9V was going to get the job done.

Now that we know a bunch of ways not to make one, it is time to actually go ahead and get the job done.

« Previous41-74 of 74
bananaskate4 years ago
oh the hu-mammary
baratacus4 years ago
wow... very cool. After seeing the pic where you used a threaded stud on a nut I got an idea for a better clasp release that won't come undone if your battery dies and your only power drain when the mechanism isn't opening would be the clap sensor..

I would suggest a small pager motor with a worm gear or a threaded tube on one side and a threaded shaft on the other side. Possibly more compact than the relay and it can not unclasp without spinning the motor. Regardless of how you facilitate it, lingere that flys off on command is just beyond amazing!

(and thank you Danica, you're an eye catcher)
Garasvaldi4 years ago
looks like much fun at parties, could you make a dress that does that?
I would think you could make a dress that does this. The easiest way I can think of is to make a babydoll type dress that has the fabric attached to a bra or boustier outfitted similar to this bra. I'd make the skirt portion very gathered with a seam down the middle in front, though the seam shouldn't come all the way up from the hem to the bra portion. For the dress to fall off properly, the opening down the middle front from the bra should be several inches wider than the hips. The fabric used for the bottom half should be fairly light-weight, and the bra/boustier would need to fit snugly.
@mariejessie good thinking, I would think there would be a market for custom dresses of this type and it sounds like you have the mind to "pull it off" as it were
Ha, good pun! I certainly could make them...but I've found I just don't like contract or production sewing! Feel free to take the idea and run with it.
I will have to look into it, I may make a hinged carbon fiber corset(I work in a company that allows me easy access to the material) do you think an electro-magnet would be a good way to go with the clasping?
I like the concept in general. What I don't like if I were wearing it is the size of the controller. For a consumer product it seems too big and bulky. However I suspect you could get it made in smaller packaging for a higher production run. You chould find a smaller mechanism for the solenoid release, though you'd need to ensure it can withstand the tension it may face when worn and can actuate properly under tension, both of which may not have been thoroughly tested for this instructable.

When you release an item for consumer use you need test it thoroughly at what you believe will be the extreme conditions. If you plan on selling this at a premium, you may also want to consider life testing if your consumer believes that the product should last a long time given the price.

Can you tell I sew as a hobby but have a degree in mechanical engineering and worked in quality engineering for many years?
drakesword4 years ago
Ok part one complete. Next do the clap on part!


Depending on the dress design you could apply the same principle.

Hell make an entire outfit then program each piece to fall off after x claps!
mariejessie4 years ago
Is this on the inside or outside of the bra? The inside would be darn uncomfortable, though I suppose one doesn't wear this type of bra for long...the outside would show, which may not be what one wants if the bra is for a 'surprise' show.
mariejessie4 years ago
Or you could sew it on. It would stay in place a bit longer that way. I'd also sew the bow into the tied formation as well, to prevent untying.
icanfixthat4 years ago
Hey Randy, Great job with this - and big points for sticking with the project and then busting out with it. ;)
When the bra is put on, the circuit in energized yes? Will it fall off when the battery dies? How long will it stay on with a 9 volt battery?

agis684 years ago
what else gonna thing sexymaniacs!...hhahahahahah...still loughing...i need also one for panties....imagine in a theater wearing this bra!!! every clap is an apocalypse and a suprise!!!...
this is a wonderful project. Kudos! I must also add that the photography is excellent as well, and i appreciate the abundance of pics to illustrate the steps along the way. very well done 'ible.

drews14 years ago
for the Gipper...
Phoghat4 years ago
Love it! It sure is a Hoot(er)
NaesDraw4 years ago
I love Instructables. I really, truthfully do. Nutella cheesecake, to clap off bras? How many other places on the internet do such things gather in one place?
Yes. I mean, no other place. Informed AND aroused ...
BamaBob4 years ago
I 'applaud' your work!
pratab4 years ago
for asgard!
missplumeau4 years ago
Ha! Ha!
Reminds me of that other model:
With a bonus for managing it one handed.
gnarkill3134 years ago
But like, what if you're wearing it in public, and someone claps? o.O
Instant hilarity!!! :p
Great job! You can make a lot of money out of those but i guess it's not the point here :D
Lindie4 years ago
As you are visiting and sleeping in the next room, did you hear me laugh out loud when I saw this ingenious idea! You are too funny! :-)
jeff-o4 years ago
I'm not sure who'd be more excited; me, or my (breastfeeding) son...
thepelton4 years ago
Clap on!
(clap clap)
clap off!
(clap clap)
katzmatt4 years ago
what is an estimated max tension that can be put on the mechanism? IE what is the max size of bra and weight of breasts this can handle?
Testers wanted.....?
angelabchua4 years ago
Probably one of the best contributions to mankind.
Kiteman4 years ago

I can think of so many people who couldn't wear this... school teachers, theatre-goers, street-performers...

Ninzerbean4 years ago
Randy you are so cute, I'm sure that if you just said "please", bras would be coming off all the time.
« Previous41-74 of 74