Straw Polyhedron 2=
span><=
/p>
Materials and tools=
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Ø &nbs=
p;
6mm or 4mm diameter straws
Ø &nbs=
p;
A ruler
Ø &nbs=
p;
A (good)pair of scissors=
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Introduction
This explanation sheet shows how to m=
ake
three dimensional-shapes with plastic straws without any glue. Each edge is connected by two apex
connectors. The connectors ar=
e also
made with plastic straws. We =
need
different numbers of straws in order to make different polyhedron. For example, to make tetrahedron a
connector needs 3 pieces of short straws and to make octahedron we use four
pieces. The following table s=
hows
required numbers of short straw.
&n=
bsp;
Table 1.=
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Polyhedron
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Surfaces=
p>
(f)*
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Number of
Edges (e)*<=
/o:p>
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Number of
Apexes (v)*
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Required number of short straws for=
1
apex connector (c)=
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Total number of short straws to make
all connectors (c*=
v)
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4
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6
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4
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3
|
12
|
|

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6
|
12
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8
|
3
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24
|
|

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8
|
12
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6
|
4
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24
|
|

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12
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30
|
20
|
3
|
60
|
|

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20
|
30
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12
|
5
|
60
|
* v + f – e =3D 2=
Three dimensional-shapes composed of
triangular shape are strong enough to keep the shape while squares and
pentagons are not strong enough. If
you want to make a good cube or 12-hedron, please apply super glue on each
apex.
Sample: How to make a skeleton of tetrahedron (4 connectors a=
nd 6
edges)
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1 In order to make a connector
prepare three 4.5cm straw pieces.
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2 Make a transverse slit at 2=
0mm
from one end of the straw. =
Do not
cut one third of the circumference of the straw.
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3 Bend the piece as the pictu=
re
above.
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4 Make a longitudinal 17mm sl=
it on
20mm part of the straw. (Le=
ave
3mm)
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5 Make two more pieces.<=
/o:p>
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6 Hold first straw then inser=
t 20mm
part of first straw into the middle hole of the longer piece of the second
straw as the picture above. (push firmly)
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7 Insert 20mm part of second =
straw
into the middle hole of the longer piece of the third straw.=
span>
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8 Put the 20mm part of the th=
ird straw
into the middle hole of the longer piece of the first straw.=
span>
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9 Combined three straws<=
/o:p>
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10 Bend all the arms of the connector down=
ward.
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11 Make a longitudinal slit on each arm. Leave 3-4mm not cut=
span>
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12 Make four connectors<=
/p>
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13 Prepare same length 6 edges.
Connect
connectors and edges.
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14 Finished tetrahedron<=
/p>
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Apply the method above to other polyhedrons=
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polyhedron
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apex
connector
close-up
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&=
nbsp;
“=
;Straw
polyhedron 2” copyright JICA Senior Volunteer Hideo Nakano (Dec 2005)