This is a design I put together for an iPhone passive amplifier. Here is the process I used to create the model in Solidworks. This process could be done just as well in Sketchup, Inventor, or Autodesk 123D.

Here is a video of the passive amplifier doing it's thing.

Step 1:

The first step was to make a box that would represent the 'dock' area for the phone to sit. I made a simple box, then added a pocket with a slight angle for the phone to rest against. This pocket was made slightly larger than the phone with a case installed on it.

Step 2:

Next, I added a small scoop like pocket on the end where the speaker is located on the phone. So the sound could be channeled out of the dock and through the horn.

Step 3:

Some fillets were added to soften edges, and a scoop from the corner where the horn will sit was taken out.

Step 4:

Some material was added to the front and back to add stability. But these will also help create decorative elements in a later step. The curved section was made to follow the horn curve.

Step 5:

Some more fillets were added and a scoop was taken out where the home button will be located. This will allow the phone to sit down in the dock, while still allowing home button access.

Step 6:

More detail and fillets were added to soften the edges.

Step 7:

Some recessed areas were added to the top just for decorative purposes.

Step 8:

The face that is selected will need a hole put in it. Depending on the production method, this can be done now or manually later.

If this item was 3D Printed, we'd want to add the element now. Whereas, if it were CNC cut (on a 3 axis machine) we can drill this hole later.

Step 9:

This is how the hole should look. It will allow for a modified bicycle horn to fit and this channel will passively amplify the sound coming from the iPhone speaker.