I was lucky enough to be bought a visualiser for my classroom. If you've never come across them before - they are essentially a piece of hardware that replaces OHPs and other projection equipment.

In class, they are used to project what is on the teachers desk onto a whiteboard.

They have some nice features - save video and still images of whats being projected, they can connect up to microscopes and you can freeze the displayed image.

All good stuff -- but they cost between £150 and £250 ($200 - $400 ish).

Having a spare web cam, I thought I could recreate one for £15 - £20 ($20 - $40).

You'll need:

USB Web Cam
Flexible neck desk lamp (cheaper the better as you'll be re-purposing it)
Software (the excellent MyScreenCam is perfect and free)
Basic tools (Dremmel / hand drill, screw drivers)

Step 1: Tear Down Web Cam / Lamp

Start with making sure that your WebCam works with your computer. Install any drivers that you need.

Then grab the excellent software MyScreenCam and install it (I have Windows 7 and it works a treat)

1) Tear down the lamp

i) Remove the inside of the lamp shade
ii) Remove any electrical wires
iii) Unscrew the lamp shade from the flexible neck

2) Tear down the web cam

i) Remove any leg / stand from the camera body.
What we are aiming for is just the camera.

Step 2: Modify the Lamp Shade

We are aiming to insert the web cam into the shade, so we need a hole in the shade big enough to take the USB connector and the ferrite core.

Enlarge the central core with whatever tools you have to hand. A drill bit / dremmel would be best.

Thread the USB cable through the shade, remembering that the camera wants to site inside the shade.

Step 3: Reasemble and Test

Reattach the shade to the flexi neck.

(In my case, the web cam fitted so snugly that I did not glue it in there - you may need to attach the camera with some hot glue)

Plug in the USB cable and fire up the software.

Step 4: Conclusion

I now have a £20 visualiser that the software allows me to project and capture the video output.

It does 80% of the functions of my Promethian for £20 as opposed to £200.

As allways, your mileage may vary.