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Modified cap for turning two-liter bottle into sharps disposal container

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MOST Delta filament as guide.JPG This page was part of an MTU course MSE4777 OA and MSE4777 OB/MSE5777/EE4777/EE5777: Open-source 3-D printing

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

Modified cap for turning two-liter bottle into sharps disposal container[edit]

Project developed by [Chris Wallenfang]
This OSAT has been designed but not yet tested - use at own risk.
This OSAT has been prototyped.

You can help Appropedia by contributing to the next step in this OSAT's status.


  1. Paragraph description of the OSAT - why is it Appropriate? What need does it fulfil? Are there case studies you have found of a technology being used successfully?
this project is appropriate because it uses post-consumer containers and an easily 3-D printable part to replace the need for manufacturing new sharps containers. 
This is a remixed cap designed to screw onto a two-liter coke bottle so that used hypodermic needles can be deposited into the container. The tapered funnel-like shape on the underside of the cap is to allow needles to more freely enter the container with reduced risk of coming back out. this lid was designed to screw on to ensure a tight fit so the lid doesn't come off [1] .  This also re-uses post-consumer plastic containers to reduce plastic waste. Due to the cheapness of this product, it can be used anywhere in the world.
  1. Picture of completed print using your printer

Bill of Materials[edit]

  1. Provide a full BOM -- Materials needed for fabrication of device and alternative materials if they are not available, prices/sources of non-printable parts
    1. Upload and link to all source files from open source CAD
    2. Upload and link to all STLs

  1. STL and OpenSCAD source can be found here

Tools needed for fabrication of the OSAT[edit]

  1. MOST Delta RepRap or similar RepRap 3-D printer
  2. OpenSCAD thread library click the link right under the "OpenSCAD modules" heading. I mainly used this to understand what the threading parameters were called in OpenSCAD.
  3. calipers to measure ID and OD of bottle top, thread pitch, height.
  4. razor blade to assist with removing print from bed

Skills and Knowledge Necessary to Make the OSAT[edit]

  • aquire a basic knowledge of threading terms and what they mean threading terminology the major diameter is the same as OD in the scad file, and minor diameter is the ID.

Technical Specifications and Assembly Instructions[edit]

  1. Provide directions for print/assembly - be detailed enough in your “how to” to ensure that someone could construct the device from your description. Consider the elegance of IKEA like instructions.
  2. Print time estimate: 48 min
  • STL file was sliced in Cura Lulzbot 3.2.27 (I added a deltabot printer as a new machine)
  • Model size was scaled up by 2% (use scale multiplier 102% in Cura) to account for possible shrinkage
  • Model included funnel shape underneath cap to minimize possibility of needles coming back out
  • Heated print bed was NOT used for printing this
  • I used a brim, however
  • Printing parameters:
1. Initial layer height: 0.4 mm
2. Layer height: 0.2 mm
3. Infill: 100%
4. Print temperature: 200°C
5. (filament) diameter: 1.75 mm
6. Print speed: 30mm/s
7. Brim width: 8mm
8. Brim line count: 5
  1. Assembly time estimate: 15 sec
Modified sharps container  
top view  

Common Problems and Solutions[edit]

  • Include common mistakes/problems to avoid in building your OSAT and how to overcome them

Cost savings[edit]

  • If your solution is not a low cost one then it is not really appropriate.
  1. Estimate your costs
  • 4 grams of PLA filament ~ $0.08
  • two-liter coke bottle: anywhere from free to $1.25
  1. Cheapest commercial equivalent for sharps container $5.89
  2. Calculate $ savings and % savings

if bottle = free: savings = $5.81 = 98.6% savings if bottle = $1.25: savings = $4.56= 77.4% savings

Benefited Internet Communities[edit]

  • Name and add links to at least 5 using single brackets around [url name]
Field Ready [1]
Medic Mobile [2]
World Health Organization [3]
Amref Health Africa [4]
World Pediatric Project [5]