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Non-electric Megaphone

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Hotend.JPG This page is part of a Principia course ENGR242: 3-D Printing Technology

Please leave comments using the discussion tab. The course runs in the Spring semester. It is not open edit.

Non-electric Megaphone[edit]

Project developed by User:Alan Freeman
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This megaphone is OSAT appropriate because there are practical uses for such a device in developing countries. A few examples would be alerting others to danger, or speaking to a crowd of people, or cheering during a sports match. Given how much electronic megaphones cost, my megaphone design is a preferrable alternative. The only way electric megaphones could be worth purchasing in developing countries would be if they were as cheap or cheaper to produce and sell than the 3D design I made.


Bill of Materials[edit]

  1. 60g of filament
  2. Click here to access the SCAD and STL files used in the printer
  3. A Jellybox 3D printer (preferrable)

Tools needed for fabrication of the OSAT[edit]

  1. Jellybox or similar RepRap 3-D printer
  2. Roughly 60g of filament
  3. A computer or SD card for holding the STL file
  4. And that's it!

Skills and Knowledge Necessary to Make the OSAT[edit]

  • If you just want to print the megaphone as is from the STL file, you don't really need any skills besides knowing how to make the 3D printer print from an SD card or laptop
  • If you want to modify the STL file a little bit, you will need to know how to use Cura to make any minor modifications like scaling the model up or down
  • To modify the design file, you will need to have experience using OpenSCAD so you fully understand what every line of code is doing. A bit of programming experience would be very helpful for this!

Technical Specifications and Assembly Instructions[edit]

  1. You will definitely want to customize the STL file in Cura
  2. When you open the megaphone in Cura, go to the "Custom" tab of "Print Setup" to make necessary changes
  3. The print will take roughly 7 hours and 15 minutes
  4. If your printer is too small to print the 100% sized design (like mine was), scale it down in Cura until it fits on the printing bed

Common Problems and Solutions[edit]

  • A problem I ran into while printing the megaphone was getting the handle to print properly
    • By default, Cura won't print supports for the handle because it is not a low enough overhang angle
    • To fix this, go to the Support section, and look for the box labeled, "Support Overhang Angle" and change this value to 45
  • My most common problem with this print was cracking and gaps between layers of the megaphone and strings in the inside
    • What helped reduce this was slowing down the print speed and going under the Material section and changing the, "Retraction Minimum Travel" distance. Doing this will lower the chance of strings on the inside.

Cost savings[edit]

  • An electric megaphone can cost £80 ($114.37), as shown here
  • Printing one megaphone of my design requires only 60g of PLA 3D printer filament
  • The average price of 1kg of generic PLA filament is $25.[1]
  • 60g is only 6% of an order of filament; 6% of $25 is $1.50. Not only is this 94% cheaper, but also allows one to print many of these megaphones. Given 1,000g of filament (1kg), this would allow one to 16 megaphones before running low on filament.


  • The sources of information (e.g. engineering handbooks, journal articles, government documents, webpages, books, magazine articles etc.). References should use the <ref> </ref> and <references/> tags and can be in any format but should include all the information necessary for someone else to find the same information you did. For example: [1]
  1. web page: Department of Energy (DOE) Landscaping and Energy Efficiency, DOE/GO-10095 (1995) Available:

Based on the developmental needs addressed (e.g. food, heat, electricity, clean water, health care, etc.) be sure to label your device in the proper categories e.g. use [[Category:Water]]. Be sure to categorize your device so that it will be easy to find – for example “Low voltage connection basics” is categorized in [[Category:How tos]] [[Category:Electricity]] [[Category:Electric lighting]].