Fig. A: Choose an object to copy, like this key.
Figs. B–D: Make a mold using casting plaster (as shown
here) or resin. Be sure to spray light oil or mold release
into the mold before using it.
CR2 lithium camera battery
Reed switch normally open type
Small piece of Constantan wire A copper-nickel
alloy, it’s sold by electronics shops.
ShapeLock or Friendly Plastic aka Polymorph in
the U.K. and Europe. All of these are polycaprolactone (PCL) plastic, a biodegradable polymer
with a low melting point.
Powdered aluminum sold by hobby or
Spatula or spoon Wood is good; use something that
won’t melt and won’t get hot in your hand.
Brass curtain rings ( 2)
Thin foam tape
1. MAKE A MOLD OF THE OBJECT
YOU WANT TO CAST.
Choose an object to copy (in this case a key) and
make a mold from casting plaster or resin (Figures
A–D). I don’t intend to provide detailed information
on how to make a mold, since Adam Savage did
such an excellent job in MAKE, Volume 08 (“Primer:
Moldmaking”). Just remember to spray some light
oil or mold release into the mold before you use it.
Photography by Andrew Lewis
Hot plate or alcohol burner
Heat gun or hair dryer
Gloves and goggles
2. MAKE AN ELEMENT WIRE.
The element wire should form a loop that passes
through as much of the object as possible, so bend
it into a suitable shape (Figure E, following page).
The gauge and length of the wire will affect the
temperature, as will the voltage and type of battery
I chose a CR2 battery, and about 5" of 28-SWG
Constantan wire. This battery and wire combination
will produce a fairly dramatic result when activated,
but it will also get hot enough to burn or even catch
fire. For safety reasons, it’s probably better to use
either a lower-voltage battery or a thinner (cooler)
gauge of wire.