This design is a slide for a spectrophotometer on an iPhone case. There are three pieces that need to be printed as part of the design. You can download the slide here and you can find the other two by going to my profile or through these links. Case: http://shpws.me/dxR8 Tube: http://shpws.me/dxSV You can print the designs through Shapeways. It is relatively cheap and you aren't paying any expenses to me.
In order to have the complete spectrophotometer, you need to have the three pieces printed and you also need to buy a linear diffraction grating (1000 lines/mm). You can find very cheap diffraction gratings on sites like ebay or amazon. Just search for linear diffraction gratings 1000 lines/mm and the gratings should be 2" X 2".
It is easy to put together the 3 printed pieces and the diffraction grating. They all slide together and the iPhone case slips on right on top of an iPhone.
The complete case is very lightweight and is easy to use. I highly recommend using the black plastic material to make the printed pieces. This is so extraneous light doesn't make its way into the tube. Don't use any translucent building material.
With this case and diffraction grating you will be able to point the end of the case at any object and you will be able to see the spectral lines for the light being emitted or reflected off of that object. You can point it at a fluorescent light, for example, and see the spectral lines for the light being emitted. You can take pictures of the spectrum with the camera on your iPhone and use them for whatever you want. You could also use it as a colorful background picture.