There are plenty of examples of how to build a USB microscope from an old web-cam out there. This design builds on those examples by using a plastic twist pack (also known as 'Bolt cases' and often used for storing machine tool cutters) to provide a cheap, elegant, robust and easy to use focusing mechanism that also protects the camera from knocks and scrapes.

Because it's robust, it's great for use by kids and in school classrooms, and if you use a decent enough camera the resulting images are easily good enough to give much more expensive, shop bought microscopes a run for their money.

This scope also has the added benefit of being able to be used facing both up and down so it provides excellent image results regardless of whether you want to look down on solid specimens or upwards through transparent, liquid samples.

It's easy to make too, no specialist tools or skills are required and the project can be completed in about an hour and for less than £10/$15.

Step 1: What you'll need

So, this is what you'll need to build your microscope:

1 x USB Webcam - I have used an xBox 360 camera from eBay 
1 x 50mm diameter, plastic 'twist pack' or 'Bolt case' - if you know someone who works with machine tools they might have a spare. I've used a DP50 050, from Rose Plastics, but I had to buy in bulk.
3 x card or MDF discs - in my original designs I used 2mm mount board, which works fine. Templates are attached.
1 x 5mm, bright white LED
1 x 220ohm resistor
20cm of thin wire (single or multicore)
1 x piece of thin, flexible card 
- I used an old cardboard tube
Double sided tape
Impact adhesive and/or glue gun

Tools that you will find handy include:

Hot glue gun
Soldering iron and solder
A scalpel and blades
Steel rule
Wire strippers
Small phillips screwdriver

what is magnification?? does i need any microscope for this
FYI the twist packs are also known as bolt cases.
Thank you, King of Clubs, I will add this in :-)
Great instructable, I plan to make a version of it using this old lab equipment I picked up recently. Might see you at BMMF on Saturday!
<p>Thank you for saying so MisterM :-) Please do drop by and say hi. The old lab gear looks magic. How did you come by it?</p>
See you there! Picked it up at the car boot, can't resist unusual old things!
you can get the &quot;bolt case&quot; from B&amp;Q they use them when selling screws and wall plugs as a set. <br>I never thought of using them for this idea which is great I will try building one for my grand children.
Great suggestion Poppy Ann :-) Just check to make sure that you can get the lens of the cam close to the bottom of whatever case/pack you select. Let me know if you source a good one :-) <br>
<p>Hi there, in the end i made one out of lego one day as i was playing with it.</p><p>sorry about the photos being all over the place they should have been the right way up when you click on them two of them come out correct but the other one gets streched across the screen</p>
Sweet! Thanks for sharing. Are you going to do a set of instructions for this scope? Would be great if you could.<br><br>Dean
<p>Hi Dean no i don't think i will be doing a instructable with it as i did not take any photos when i was building it i just threw it together one day when i needed one as i was doing some soldering on very fine SMD items and by using this i could make it as large as the screen i think it is around 75 times magnification i think if i wanted to go any larger it would need a better lens.</p><p>regards Poppy Ann. </p>
<p>Well you project is better that me because it'pretty neat!</p>
Or you could use 3 inch diameter PVC threaded fittings at the Big Orange Box. Make an optical stage for the objective out of a disposable camera. and viola you have a zoom scope from a 3 dollar USB cam. Dont forget to pull out the IR blocking filter so you can do multi spectral imaging with a vinyl gel filter pack from your lighting supply company on eBay
You should create an Instructable for this! :-)
Can you detail a little more about how you focus? You said at one point &quot;albeit a quite hard to focus microscope, but we'll soon sort that out&quot; but try as I might, I don't see where you sorted it.
Further to my last reply, I've updated step 9 to try and make things a little clearer :-)
That's a really, really good point, thank you for calling it out :-) <br> <br>Basically, with the camera mounted inside one half (what I refer to as the upper half) of the twistpack/bolt case, as you twist the two halves the the camera lens moves up and down enabling you to achieve a controlled focus as you view. <br> <br>Just make sure you have the lens within a couple of millimetres from the base of the pack/case at its' shortest height when you build your scope and you will be able to get good focus. <br> <br>Does this help?
Really nice one!
Thank you :-) <br>
Why not remove the green ring LEDs and take power from their circuit to illuminate the subject being magnified? This circuit turns off when the camera is not being accessed, thus not on all the time as in your instructions? <br> <br>DieCastoms
Thanks DieCastoms, yes it might be quite fiddly but you could do this. Alternatively you could just unplug the microscope when you are done :-) <br> <br>Part of the reason I took the approach I did is because it works pretty consistently across different kinds of camera.
What would you rate the zoom on the xbox camera to be at? 10 times 100 times 250...?
I still need to work this out :-) <br>What I will say is that it is a very acceptable magnification for getting people interested in exploring what is beyond their normal sensory ability.
Great Post...!!! Outstanding stuff for do it yourself scientific equipment so you can do your own scientific investigations....!!! <br>
Thank you, that's very kind of you to say :-)
good one
good one

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