Introduction: Magnetic Field Line Viewers

About: I play with light

These are two low-cost methods to make individual magnetic field line viewers from household or classroom items, iron filings, and reused plastic packaging. We can use them to teach about magnetism while simultaneously reinforcing conservations and recycling practices by repurposing waste items.

If you spend any time around kids (or cancer patients like I do), you end up going thought a lot of hand sanitizer. Hospitals are always giving away tiny bottles, so I started saving the empties while I considered how to reuse them. A few days ago, I was playing with magnets and recalled how much fun magnetic field line viewers were. So I set out to make some small viewers for students.

Because magnets are so much fun to play with, and plastic packaging is everywhere, I also decided to make a flat viewer similar to a beloved childhood toy. For this, I used empty clamshell plastic from card game packaging.

  • If you want to make the bottle version simply continue to step 1
  • Incidentally, any clear plastic bottle will work, but 4oz flat-sided bottles are my favourite for this.

  • If you only want to make the clamshell version skip to step 7


Children should be supervised at all times when playing with magnets. Magnet ingestions pose a serious health threat. Only use magnets that are too large to swallow and never use neodymium (rare earth) magnets. These magnets are too powerful for children to play with safely. Neodymium magnets are also nickel-plated and can cause an allergic reaction.


Bottle Version:

  • Small Plastic bottles
  • Iron Filings
  • Magnets
  • Mineral Oil
  • (Electrical) Tape

Flat Version:

  • Plastic Clamshell Packaging
  • Cardstock
  • Knife or Cricut Air
  • Ruler
  • Iron Filings
  • Magnets
  • Quick Drying Glue
  • (Painters) Tape


  • Spray Adhesive
  • Corner Rounder Paper Punch
  • Paint
  • Washi Tape
  • Stickers
  • Decorative items of your choice

Step 1: Bottle Prep

  • Wash the bottles and caps with warm soapy water
  • Remove the labels
  • Air dry

Step 2: Add Iron Filings

Use a small to add a small amount of iron filing to the bottle

Step 3: Add Mineral Oil

  • Add mineral oil to the bottle
    • Fill ~90%
  • Use a magnet to check that you are happy with the amount of iron filings
    • Add more iron filings if necessary
  • Fill with mineral oil

Step 4: Cap Bottle

  • Cap the bottle tightly
  • Secure with electrical tape to prevent any curious little gremlins from opening it.
    • Add a strip of tape across the top of the cap
      • This should secure the flip-top to the body of the cap
    • Add a second strip of tape perpendicular to the first one
  • Wrap tape around the cap and the top of the bottle.

Step 5: Give It a Backdrop

  • Place a piece of light-colored cardstock on one side of the bottle.
    • It makes it easier to see the iron filings
    • It will keep the magnet from scratching the bottle


Decorate your bottle. Use stickers, washi tape, paint or whatever else is interesting to you.

Step 6: Play

  • Remove the magnet
  • Shake the bottle
  • Place a magnet on the bottle
  • Watch the iron particles line up with the magnetic field lines

Step 7: Measure Clamshell

  • Measure the external dimensions of the plastic shell
  • Record length, width, and height
    • These will be necessary to make the frame for the Magnetic Field Line Viewer

Step 8: Prep Frame Parts

  • Use the measurements from the previous step to cut out the three parts for the frame
  • Simply make your frame parts to fit whatever plastic blister pack of clamshell you would like to use
  • The cutout in the front of the frame should be a little smaller than the cutout in the back of the frame to hide the glue.
  • There are two versions of the basic template:
    • V1 gives you a single plain Background
    • V2 also gives you a plain Background but allows you to insert a drawing or photo
    • There is no real difference in assembly
  • The broken lines in the template represent folds and are the height measurement of the clamshell
  • Since I am making dozens of these, I used a Cricut cutter. However, you can easily cut out the frame with a knife and straight edge.

Step 9: Cut Hinge

  • Take your knife and cut off the hinge
    • This will allow the pieces of the frame to sit flat again each other

Step 10: Add Iron Filings

  • Remove lid and set aside
  • Place a small magnet under the plastic clamshell
  • Sprinkle a small amount of iron into the plastic base
    • I used about 1/4 tsp
  • Leave the magnet in place

Step 11: Secure Lid

  • Use a small paintbrush to "paint-in" glue to the top lip of the base
  • Install the lid
  • Use binder clips to hold the pieces together until the glues is dry
    • I used tape to help keep the pieces together and as a redundant measure to prevent any iron fillings from escaping

Step 12: Frame - the Background

  • Fold the Background (white cardstock) into shape if you haven't already
  • Place the plastic clamshell in the Background

Step 13: Frame - Backround + Back

  • Thread the clamshell + Background (white cardstock) through the cutout in the Back (gray cardstock) of the frame.
  • Glue in place

Step 14: Frame- the Front

  • Align the pieces of the frame
  • Secure in place with glue


Binder clips can be used to hold the frame together while the glues dries

For a shorter dry time, use spray adhesive to coat the underside of the Front part of the frame then press all the pieces together

Step 15: Get Creative

Try using different sizes of blister packs or clamshells.

Consider adding a design to the background

Remember Wooly Willy? You can add a photo or a drawing to the background or make them interchangeable if you used the V2 Background.

Perhaps a photo of yourself or your pet will encourage some magnetic doodling.

You can make a stylus, however, a safer option (for small children) is to simply order one or two :)

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