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Benjamin Wang
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An icosahedron has 20 faces which are equilateral triangles.

enter image description here

Tom wants to create a very hard mechanical puzzle. With his brand new 3D printer in mind he designs 20 puzzle pieces with identical shapes which in principle nicely fit together to build the icosahedron:

enter image description hereThe visible

The face ofthat is visible after assembling the assembled icosahedron is on the back here.

To hold the parts together he uses magnets which he glues into the prepared 5 holes in athat he had prepared quite devilish waydevilishly.

There are exactly 10 ways to orientateorient the magnets such that two magnetmagnets are orientated to the outsideoriented with the north pole, thesepoles facing outwards. These 10 parts he wants to print in yellow. Here is one example:
enter image description here

And of course there are also exactly 10 ways to orientateorient the magnets with two south poles to the outsidefacing outwards. These 10 parts he wants to print in blue. Example:

enter image description here

Hey, we got a complete set of exactly 20 different pieces! There are $19!*3^{19}$$19!*3^{19}> 10^{26}$ ways to assemble the icosahedron if we ignore the magnets.

  1. So should notIs at least one ofway for the more than $10^{26}$ combinations hold nicely togethermagnets to match everywhere (north poles matchto south poles everywhere)?
  2. And to top it all, isAre there eventually an especially nice looking solutions with 5 fold-fold symmetry? TheObviously, only the colors of the pieces obviously are only interesting for this part.

An icosahedron has 20 faces which are equilateral triangles.

enter image description here

Tom wants to create a very hard mechanical puzzle. With his brand new 3D printer in mind he designs 20 puzzle pieces with identical shapes which in principle nicely fit together to build the icosahedron:

enter image description hereThe visible face of the assembled icosahedron is on the back here.

To hold the parts together he uses magnets which he glues into the prepared 5 holes in a quite devilish way.

There are exactly 10 ways to orientate the magnets such that two magnet are orientated to the outside with the north pole, these 10 parts he wants to print in yellow. Here is one example:
enter image description here

And of course there are also exactly 10 ways to orientate the magnets with two south poles to the outside. These 10 parts he wants to print in blue. Example:

enter image description here

Hey, we got a complete set of exactly 20 different pieces! There are $19!*3^{19}$ ways to assemble the icosahedron if we ignore the magnets.

  1. So should not at least one of the more than $10^{26}$ combinations hold nicely together (north poles match south poles everywhere)?
  2. And to top it all, is there eventually an especially nice looking solutions with 5 fold symmetry? The colors of the pieces obviously are only interesting for this part.

An icosahedron has 20 faces which are equilateral triangles.

enter image description here

Tom wants to create a very hard mechanical puzzle. With his brand new 3D printer in mind he designs 20 puzzle pieces with identical shapes which in principle nicely fit together to build the icosahedron:

enter image description here

The face that is visible after assembling the icosahedron is on the back.

To hold the parts together he uses magnets which he glues into the 5 holes that he had prepared quite devilishly.

There are exactly 10 ways to orient the magnets such that two magnets are oriented with north poles facing outwards. These 10 parts he wants to print in yellow. Here is one example:
enter image description here

And of course there are also exactly 10 ways to orient the magnets with two south poles facing outwards. These 10 parts he wants to print in blue. Example:

enter image description here

Hey, we got a complete set of exactly 20 different pieces! There are $19!*3^{19}> 10^{26}$ ways to assemble the icosahedron if we ignore the magnets.

  1. Is at least one way for the magnets to match everywhere (north to south)?
  2. Are there especially nice looking solutions with 5-fold symmetry? Obviously, only the colors of the pieces are interesting for this part.
added 5 characters in body
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An icosahedron has 20 faces which are equilateral triangles.

enter image description here

Tom wants to create a very hard mechanical puzzle. With his brand new 3D printer in mind he designs 20 puzzle pieces with identical shapes which in principle nicely fit together to build the icosahedron:

enter image description hereThe visible face of the assembled icosahronicosahedron is on the backsideback here.

To hold the parts together he uses magnets which he glues into the prepared 5 holes in a quite devilish way.

There are exactly 10 ways to orientate the magnets such that two magnet are orientated to the outside with the north pole, these 10 parts he wants to print in yellow. Here is one example:
enter image description here

And of course there are also exactly 10 ways to orientate the magnets with two south poles to the outside.These These 10 parts he wants to print in blue. Example:

enter image description here

Hey, we got a complete set of exactly 20 different pieces! There are $19!*3^{19}$ ways to assemble the icosahedron if we ignore the magnets.

  1. So should not at least one of the more than $10^{26}$ combinations hold nicely together (north poles match south poles everywhere)?
  2. And to top it all, is there eventually an especially nice looking solutions with 5 fold symmetry? The colors of the pieces obviously are only interesting for this part.

An icosahedron has 20 faces which are equilateral triangles.

enter image description here

Tom wants to create a very hard mechanical puzzle. With his brand new 3D printer in mind he designs 20 puzzle pieces with identical shapes which in principle nicely fit together to build the icosahedron:

enter image description hereThe visible face of the assembled icosahron is on the backside here.

To hold the parts together he uses magnets which he glues into the prepared 5 holes in a quite devilish way.

There are exactly 10 ways to orientate the magnets such that two magnet are orientated to the outside with the north pole, these parts he wants to print in yellow. Here is one example:
enter image description here

And of course there are also exactly 10 ways to orientate the magnets with two south poles to the outside.These parts he wants to print in blue. Example:

enter image description here

Hey, we got a complete set of exactly 20 different pieces! There are $19!*3^{19}$ ways to assemble the icosahedron if we ignore the magnets.

  1. So should not at least one of the more than $10^{26}$ combinations hold nicely together (north poles match south poles everywhere)?
  2. And to top it all, is there eventually an especially nice looking solutions with 5 fold symmetry?

An icosahedron has 20 faces which are equilateral triangles.

enter image description here

Tom wants to create a very hard mechanical puzzle. With his brand new 3D printer in mind he designs 20 puzzle pieces with identical shapes which in principle nicely fit together to build the icosahedron:

enter image description hereThe visible face of the assembled icosahedron is on the back here.

To hold the parts together he uses magnets which he glues into the prepared 5 holes in a quite devilish way.

There are exactly 10 ways to orientate the magnets such that two magnet are orientated to the outside with the north pole, these 10 parts he wants to print in yellow. Here is one example:
enter image description here

And of course there are also exactly 10 ways to orientate the magnets with two south poles to the outside. These 10 parts he wants to print in blue. Example:

enter image description here

Hey, we got a complete set of exactly 20 different pieces! There are $19!*3^{19}$ ways to assemble the icosahedron if we ignore the magnets.

  1. So should not at least one of the more than $10^{26}$ combinations hold nicely together (north poles match south poles everywhere)?
  2. And to top it all, is there eventually an especially nice looking solutions with 5 fold symmetry? The colors of the pieces obviously are only interesting for this part.
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Can you assemble the icosahedron?

An icosahedron has 20 faces which are equilateral triangles.

enter image description here

Tom wants to create a very hard mechanical puzzle. With his brand new 3D printer in mind he designs 20 puzzle pieces with identical shapes which in principle nicely fit together to build the icosahedron:

enter image description hereThe visible face of the assembled icosahron is on the backside here.

To hold the parts together he uses magnets which he glues into the prepared 5 holes in a quite devilish way.

There are exactly 10 ways to orientate the magnets such that two magnet are orientated to the outside with the north pole, these parts he wants to print in yellow. Here is one example:
enter image description here

And of course there are also exactly 10 ways to orientate the magnets with two south poles to the outside.These parts he wants to print in blue. Example:

enter image description here

Hey, we got a complete set of exactly 20 different pieces! There are $19!*3^{19}$ ways to assemble the icosahedron if we ignore the magnets.

  1. So should not at least one of the more than $10^{26}$ combinations hold nicely together (north poles match south poles everywhere)?
  2. And to top it all, is there eventually an especially nice looking solutions with 5 fold symmetry?