These three magnet bodies are designed for any whiteboard or other magnetic surface to help keep you organized.
Design features
The bodies are 33 mm in diameter, which should pass the small parts test for children under 3 years old (please supervise your children and use your judgment at all times).
The magnet is fully embedded and can't be removed (safer than a glued-on magnet).
The half dome shape is deliberately hard for small children to manipulate once it's on a surface.
When printing in flex filament it will hurt less when thrown. Also makes a good bumper for cabinets and refrigerator doors depending on the placement of your magnetic board in the kitchen.
There are two magnet sizes already rendered for each style, 20x5mm and 25x5mm.
Hole version
The style with holes easily accommodates a 2 mm poly cord with no core (such as this one).
There is nothing special about this, except that the lack of any interior structure makes it super squishy.
Printing instructions
Choose the version you want (style and magnet size).
I recommend flex with 10% infill.
Slice the .stl file to include a pause after the magnet cavity (around 6.1 mm, depending on your layer height).
Insert the magnet during the pause (glue isn't necessary for flex material, but if you're using something hard it will prevent rattles). Check that the magnet orientation is suitable for your use.
Note: The .gcode file I've included has a custom pause algorithm. Upon resume it will extrude a bit and begin a 4 second move to give you time to wipe excess material.
Usage instructions
Hole style
Use a rope cutter (or flame) to get clean ends.
Each axis has a choke point on one side (look carefully to identify it). If you're tying a knot, place the knot outside the choke point (away from the centre).
A double overhand knot should be plenty to keep the cord in place. Leave a bit on the end if you want to pull it out easily later on.
There's enough room inside for two cords to pass each other perpendicularly (you might need a toothpick to help feed them).
Other styles
Please experiment with the best ways to use them and upload pictures of your makes!
Safety notes
Magnets can be dangerous.
Please supervise your children at all times.
Notes
I designed this model in OpenSCAD and it's fully parameterized. If you'd like a simple modification (i.e., magnet size), send me a message and I'll see what I can do.