This is a mini styrofoam cutter you can build in 1 our or so.
With this little device you can cut through styrofoam and thin plastic sheets.
Step 1: Things You Need
You will need:
a hot glue stick
some steel rod about 3mm thick
a short piece of steel tube with the same diameter as the wire
Resistance wire 0,15mm (mine's got a resistance of about 28 ohms per meter)
perhaps some flux
something to draw a straight line
Step 2: The Main Board
Take a piece of plywood and mark a rectangle - I chose 90 x 125 mm.
Then take a jigsaw and cut it out. Take a piece of sandpaper and smooth the edges.
Now locate the center of your rectangle and draw a line through it (shown in the picture). Take your drill and drill one hole with a diameter of about two millimeters and one hole with the outer diameter of your iron\steel tube.
Step 3: The Feet
Take your hot glue stick and mark four pieces with a lenght of about 1 cm.
Now take your torch and heat your knife untill it can cut through hot glue easily (for this messy job I used a knife which costs about 4 dollars)
Cut the four pieces and glue them into the corners of the board.
Step 4: The "arm"
Take your steel rod and heat it.
Now take your pliers an bend the steel rod about one centimeter from its end.
Take your tube and put the bent over end into it.
Heat up your soldering iron and make a strong connection between the rod and the tube.
If you want to you can take a file and a sandpaper to smooth down the excess solder.
Step 5: The Wire Holder
Take a nail and trim off the ends.
Now choose a cable and strip the ends off.
Wrap it around the end of the nail and solder it in place.
Take your resistance wire, make a loop around the nail and twist the ends together. If you want to you can make a little grove to prevent it from sliding around.
Step 6: Assembly
Take the nail with the resistance wire on it and put the wire through the 2mm hole.
Then secure it with a piece of electrical tape.
Now take your "Arm" and put it into the hole you drilled earlier for it.
After this secure it with some epoxy and let it sit for about 24 hours.
When the Epoxy is hard enough you can take the wire and connect it to the arm as shown in the pictures.
Make sure the resistance wire is under constant tension.
Step 7: How to Use
Connect the metal tube and the cable from the wire holder to a power source (in my case a bench top power supply)
and you are ready.
The hot wire cutter can easily cut through styrofoam, house insulation and plastic foils.
It draws about 1.2 amps at 2.3 volts but the current depends on what kind of resistance wire you use.