Milk Jug Shovel

Growing up, I lived in a small town and often had to drive to the next town when I needed anything. As a kid I was taught to be resourceful and the importance of giving things a second life. Now, as a student of the life sciences, I understand the importance of this even greater.

Within the past few years, my friends and family have begun to settle down and have kids. Recently a few friends of mine decided to plan a beach trip since it had been a while since we had all been able to get together. Knowing they would bring their young kids, I decided to make some beach toys for them to play with.

For this project, I designed a reusable handle to turn a milk jug into a simple shovel. For families with children milk jugs always seem to be around and often end up in the landfill. This design allows for these milk jugs to have a second life while also creating something fun for the kids.

• Ender 3 pro
• Pla filament
• Autodesk Fusion 360
• Cura or equivalent slicer
• Calipers
• Milk jug
• Razor blade or hobby knife
• Super glue
• Sharpie or equivalent marker

To begin I roughly cut apart a milk jug to remove its handle. Using my calipers, I first measured the distance between the two holes in the handle and their diameters. After this, I then measured the full length of the handle. From here I used a protractor to determine the interior angles of the handle and again the caliper to measure their depths. Once I had some numbers, I then began to sketch the design in fusion360.  To give the little hands somewhere to grip, and the milk jug handle needed rigidity, I designed a part that would slide into the two holes of the milk jug handle. This part would need to “snap” into place and avoid moving, so I extruded it to the largest size to fit the diameter I could.  I also attempted to add curves to the design to remove breaking points which, while they worked, worked better in theory.  

               Though this part worked, I worried the blade would not have enough rigidity. To combat this, I then designed a second part that would add needed bracing to the back of the blade. For this, I designed a set of “fins” that could sit at the front of the handle to prevent the plastic jug from bending. While I was designing this part, I also began to worry about the milk jug plastic possibly cutting the small hands. This then led to the inclusion of an extended cover for the handle.

For printing, I used a Inland Cornflower Blue pla to match the beach aesthetic. I printed both parts without support using my mostly stock Ender 3 pro. Since neither part had overhangs or steep angles, I was able to print them without supports. While I believe that another filament like petg of abs might be a better fit for this project, I currently only print in pla. To compensate for some of pla weaknesses I increased my wall count from 3 to 5 walls.

Hotend: 200 C

Bed: 60 C

Print Speed: 50 mm/s

Layer height: 0.28 mm

Starting with a new jug, I sketched onto and roughly cut the milk jug to remove the handle and a sizable piece of plastic. Placing the hooked end of the first print into the interior hole of the milk jug, the back end quickly snapped into the remaining hole. Using a razor, I removed excess plastic around the back hole and printed handle. Once clear, I then dry fit the second printed part to feel for any remaining plastic protruding around the handle. When I felt it would be safe for small hands, I then applied a layer of super glue onto the handle and pressed the fins into the back of the blade.  After applying pressure to ensure a tight fit, I flexed the blade to ensure the fins were doing their job. Happy with the result, I then again used the razor to shape the blade to a more defined shovel shape. I found that when cutting the blade or the shovel I needed to make a much wider blade than first expected to compensate for the flexibility of the plastic.

I want to mention that with repeated removal testing the first printed part it eventually cracked. After reprinting with a greater number of walls, 5, the part continued to crack at the same point which may be an issue with the design. Even with the lesser number of walls I never experienced a full part failure or was pinched by the design. It seems that the pressure of flexing the part into place may create too much of a bend though it reseats back into place once set. As mentioned earlier I do feel that this problem could be resolved by using a different filament. That being said, even with the crack,  once fully assembled I have not had any issues with the final product.

With the shovel complete all that was left was for some test. Since I do not live at the beach, I decided to test the shovel using some potting mix I had at the house. As you can see the shovel worked great and the fins helped give the additional strength it needed. Though the design worked great I would say it is best suited for a kids toy as the flexibility of the milk jug plastic prevents it from cutting into harder earth. Though this may be the case, I still believe this will provide many hours of fun at the beach or sandbox and can always be attached to a new jug when the old one finally gives out. Just remember to recycle the old one when finished.  

If interested in printing feel free to download the files below and post any remix you may make:

https://makerworld.com/en/models/482950