We all know the problem when you've been to the toilet for some big business. While washing your hands you think: 'just air-freshner is not enough! There should be a way to warn innocent visitors to stay away from this place for a little while.'

This biohazard warning is the solution for this global problem.

Just set the timer for the hazard you left and in time the warning scale will turn to 'safe' again.

It is an easy and cheap build. The only thing I bought for this project is a cooking timer. I mostly used trash materials and scraps.

Step 1: You will need


  • packaging (trash) cups
  • cooking timer
  • something to use as backboard


  • scissors
  • hobby knife
  • sharpy
  • glue
  • color-printer


  • paint
  • hole-punch
  • tools to create the backboard

<p>That is cool ^^</p>
<p>clever, cheap and most of all a nice prank!!!</p>
Well, in my house we use it now for real and not as a prank, but you are right, I didn't build it really serious :)
<p>very strange but very cool....double plus good...got my vote....</p>
<p>Very Clever XD</p>
Thank you
<p>Your welcome :)</p>
<p>Now that is one cool project! :)</p>
thank you
<p>Somehow this makes me think of the movie "Friday", the one with Ice Cube in it? </p><p>Nice!</p>
<p>I don't know that movie, but you made me curious about it.</p>
<p>Here's the <a href="https://www.youtube.com/watch?v=of49fNcdqa4&feature=kp" rel="nofollow">Friday Reference</a>. I've used this line many times and no one gets it!!</p>
<p>Yes that is definitely what this timer is about :)</p>
<p>So now your next step is to replace the timer with a hobby servo, then just add an Arduino and one of these <a href="http://www.sainsmart.com/sainsmart-mq-4-methane-gas-sensor-natural-coal-co-detector-module-for-arduino.html" rel="nofollow">SENSORS</a> and you are done!</p><p>By the way folks... if you put in a link... highlight the text, then use the chain icon to past the actual link... then it becomes clickable like this...</p><p><a href="http://www.sainsmart.com/sainsmart-mq-4-methane-gas-sensor-natural-coal-co-detector-module-for-arduino.html" rel="nofollow">http://www.sainsmart.com/sainsmart-mq-4-methane-gas-sensor-natural-coal-co-detector-module-for-arduino.html</a></p>
Jerry,<br>Good idea with one exception, you'd need a hydrogen sulfide detector and not a methane detector. That and I'd hate to have to be the one to do all the testing required to calibrate a digital stink sensor.
<p>Using an Arduino would be my first choice, so I really liked to do this cheap and low-tech. </p><p>Somehow I didn't find the chain icon when typing a reply. So thank you for the advise. </p>
<p>1) Type in text.</p><p>2) Highlight the text</p><p>3) A popup should appear with</p><p>&quot;B&quot; (bold) &quot;I&quot; (italic) &quot;H&quot; (heading) &quot;chain icon&quot; (link) &quot;quotes&quot; (block quote)</p><p>Here is what they look like when done...</p><p><strong>BOLD</strong></p><p><em>ITALIC</em></p>HEADING<p><a href="http://youtube.com/askjerry" rel="nofollow">LINK</a></p><blockquote>BLOCKQUOTE</blockquote>
<p>you should make an Ible on how to use the new comments systerm</p>
<p>I found it, thank you</p>
<p>Did you use an IKEA cooking timer?</p>
<p>No, it is from a Dutch brand called <a href="http://www.hema.nl/winkel?fh_location=%2F%2Fnlhema%2Fnl_NL%2Fpnl_product_type%3E%7Bbooks%3Bshop%7D%2F%24s%3Dkookwekker&fh_secondid=pnl_80852059" rel="nofollow">HEMA</a>.</p>
<p>VERY GOOD but is it possible to change the size of the circles in the pdf? or do I have to find a very look alike of those sizes so I can make this?</p><p>PLEASE answer...</p>
<p>In most printer-drivers it is very easy to resize it when you print. You can also import the PDF in an other document as a illustration and resize it there. If you have Adobe Illustrator, you can open the PDF in Illustrator (CS2 or newer) and change anything you want about it. The PDF document is an Illustrator PDF.</p>
<p>Nice. I believe you are missing the Chernobyl level indicator on the scale, especially when it is monster burrito night. You can't go back in for at least a thousand years.</p>
<p>Years later, the landscape was never the same since the meltdown...</p>
<p>This should be added to the building codes in Texas. All we ever eat is mexican and tex-mex (Like mexican but hotter). You have to be a desperate fool to enter a bathroom after another man comes out, you got to give it time to breathe!</p>
<p>We don't have burrito nights here, but we probably make up for that with 'bruine bonen'. So a special 'bruine bonen' or burrito setting might be a good idea :)</p>
<p>Ah, in English...Beans, beans, they're good for your heart, the more you eat, the more you far......</p>
<p>I seemed to have an unexpected brain stoppage but you managed to squeeze that out.</p>
<p>Beans, beans, the musical fruit. The more you eat, the more you toot! The more you toot, the better you feel. So let's have beans for every meal!</p>
<p>That was a quote from Shakespeare?</p>
<p>Friends, Romans, countrymen, I had garlic cabbage last night. Sorry.</p><p>To be, or not to be, that is not the question. To go into the throne room after Rosencrantz or Guildenstern have left, that is the question. </p>
<p>there are probably laws that force you to build this :)</p>
<p>Cry Havoc! and let loose the kimchee of war...</p>
<p>it should be :)</p>
<p>If my history recollection is correct, he wrote it for Macbeth but it didn't make the cut.</p>
<p>That was exactly what inspired me for this project. Everybody knows Macbeth was a real stinking dude on the outhouse. But that also didn't make the cut. :)</p>
<p>never heard those last two lines, thanks for helping me annoy my &quot;friends&quot; even more!</p>
<p>Hahahahha, it's funny and practical! : D</p>
<p>Thank you</p>
<p>Clever, funny and entirely practical. Every home should have one of these.</p>
<p>yes that was my idea :)</p>
<p>Did you remove the bell also? </p>
<p>Well the housing was the bell, so it still kind of purrrrrrs, but it doesn't ring anymore.</p>
Cool! :-)
<p>Thank you</p>
<p>Very nice idea, even better execution!!!!!</p>
<p>Thank you</p>
<p>Very interesting. </p><p>I think the problem with this should be that those who need to use it, they will ignore.</p>

About This Instructable


509 favorites


Bio: I'm a social-worker, working with 12 - 23 year-olds. I used to be a printer and I worked voluntarily in Romania for a couple of ... More »
More by kenyer: Let's make collective toilet art Pinewood Derby Race Pimp your Medicine Cabinet
Add instructable to: