Introduction: Design an MP3 Amplifier Using Autodesk Inventor

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Ever want to share the tunes from your MP3 player, but only have those little ear buds? In this tutorial, we’ll walk through the design for the case for a simple tool that can be used to amplify your MP3 player.

If you’re a teacher, encouraging students to design objects with real world application is a great way to engage their creativity, as well as push them to think critically and use design skills. You can find a complete lesson plan devoted to this project, as well as instructional materials like learning objectives, test materials, and evaluation rubrics below.

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Step 1: Download Autodesk Inventor

Before you start, download and install Autodesk Inventor here (it's available with a free 3 year license for students and educators). Inventor offers an easy to use set of tools for 3D mechanical design and product simulation. If you want a general tour of the interface, commands, and different ways you can use Inventor, see information on getting started here.

Step 2: Sketch MP3 Case

Create a rectangle representing the outside edge of the case. Use the offset tool to create a smaller rectangle inside. Extrude the rectangle to make a 3D model. Soften sharp edges using the Fillet tool.

Use the project geometry tool on the underside of the case to create a sketch. Extrude that sketch just enough to create a back plate for the case. Use the hole tool to create holes in the back plate.

Use the project geometry tool on the topside of the case to create another sketch. Use the offset tool to create a sketch slightly larger than the interior rectangle. To create space for the screen to be placed later, extrude this new shape (cut) downward.

Sketch a hole for the power cable on the side of the case. Extrude (cut) the hole. Repeat this process to create a hole for the auxiliary cable.

For a step-by-step video tutorial on this stage, see:

Step 3: Sketch Component Holder

Before you sketch the component holder, open a new part. Draw a rectangle for the edge of the component holder, and draw one circle on one side for a speaker opening. Use the Mirror tool to create a second identical speaker hole.Then, extrude the 2D model to make it 3D.

Create a space for the PCB Unit by creating a rectangle and Extruding. Use the Hole tool to create holes for attaching the PCB unit. Lastly, use the Fillet tool to round off sharp edges.

For a step-by-step video tutorial on this stage, see:

Step 4: Design the Grill

Open a new part. Sketch a rectangle, Extrude, and Fillet the sharp edges.

Using the Hole tool, drill one hole into the grill. Use the Rectangular Pattern tool to cover the grill with holes. Suppress some of the holes to make space for volume control.

Lastly, use Hole tool to make a larger hole for volume control.

For a step-by-step video tutorial on this stage, see:

Step 5: Design the Volume Control Knob

Open a new part. Sketch a Circle and Extrude it.

Sketch a smaller circle in the center and Extrude it into the knob.

Extrude a third circle, in between the larger and smaller circle, to a shallower depth.

For a step-by-step example of this step, see:

Step 6: Assemble the Case

Open a new file and Insert the case that you made at the beginning. Insert the component holder, and snap it into place.

Insert speakers from the resource pack, and snap them into place. Do the same thing with the PCB Unit.

Insert the Grill that you designed earlier and snap it into place. Do the same thing with the volume control knob.

For a step-by-step video of this stage, see:

Step 7: Print!

In order to print parts from Inventor on your MakerBot you will need to export your file as an STL. You will also need to download and install the latest version of the Makerware™ software from MakerBot. The software is free of charge and can be downloaded here.

Once a part has been created and is ready for printing you can select "Export" from the Application Menu, then "CAD Format." In the dialog box that pops up, select .STL in the "Save as Type" dropdown.

Once you have exported your file as .STL, open it in Makerware. Adjust your prototype as necessary, and click the "Make" button. Select your printer and materials, and send it to the printer!

If your printer doesn't run Makerware, you can still export an .STL file, which will allow you to use any software your printer requires. Lastly, if you don’t have a 3D printer, places like TechShop have the tools to turn your design files into physical objects, and staff the people who can show you how. Places like Shapeways can even print them for you.