Make your own hot-wire or styrofoam cutter

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Last modified on: July 1st 2021


Filicutter is a tool to hot cut styrofoam, which allows you to highlight any piece recovered, and do so a lot of things: modeling, layout, visual arts, etc ...

Filicutter principle 1

The principle is quite simple, there is a strong electric current in a thin resistive wire. The wire under the effect of current, heat and cut easily and cleanly styrofoam, much much better than with a knife or a cutter, particularly for large pieces (> 5 cm thick). It can also be use to cut plastic or synthetic foam.

Build a filicutter is only adding a current source to resistive electrical wire, adding a control switch and possibly a light bulb to limit a bit the current passing through the wires.

Filicutter principle 2

And of course mount the whole on a structure, insulated, easy to handle, so you can control the hot wire during phases of cut. The idea was to do something that looks like a bit to a saw wire, a kind of huge "U" who owns a handful at the end. Like this:

Filicutter principle 3

This way you control switching on/off heater wire with a finger, and guide cutting with the same hand.

What you need

How to

When you've read the principle, you can do it in your way. Here is mine, made with resistive wire and car battery charger.

Fold metalic pipe to make the "U" according to your dimensions.
Cut the handle in plastic pipe. On top of this pipe, make (using a saw) a place for the "U". Make a hole for your push-button, in the right place for your finger as a trigger. Connect two wires to push-button, and put them inside the handle. filicutter
Put the "U" in the handle, let 2 cm - 1 inch exceed, and fix it by making two holes througt the handle. Put two bolts in those holes, and put two nuts on the other side. You should have in your hand something light, with push-boutton right under your index. filicutter
Add then the resistive wire on the "U". On top, use a small metallic bolt with a ring head. You shoud use metallic bolt because and electric contact is needed on that side. filicutter
On bottom, contrarily wire should be insulate from the "U": use a small piece of wood, fixed with another bolt and nut, then another metallic bolt with a ring head. filicutter
Then connect:
  1. One arrival of power to the "U" (using an alligator clip for example).
  2. The other power arrival on one probe of the push-buttonl
  3. The second probe of push-button to the bottom metallic bolt with a ring head

That's it, it's over, you can now discover the happiness of precision cutting styrofoam...

Alain told me that you should be careful with styrofoam smokes when cutting, they are toxic and should not be breath.


Filicutter with handle like this one is very useful for... sculpturing styrofoam, but it's a bit difficult to make straight cuts.

If you have this kind of cuts to do, it could be interesting to improve it by making a kind of stand. The idea is to make this stand with a right-angle system and another push-button commanded by your feet, so that your two hands are free to control the styrofoam piece move.

To do that, you should make a small table, with a hole in and where the wire pass through. Table and filicutter should be in right angle, stable and connected, for example in a clamp.


Home made filicutter

Here is some photos of mine (click to enlarge) :

filicutter filicutter filicutter filicutter

Grip detailTop nail detailFixing detail
filicutter filicutter filicutter filicutter
Connected to a car abatterry chargerWorking on claw-back styrofoam pieceSharpen curtCutting table...
filicutter filicutter filicutter filicutter a clamp.Filicutter in p.laceFeet action
filicutter filicutter filicutter filicutter
Also cut shapes...
filicutter filicutter
more complex.Also cut foam


You could now, according to your needs, enhance the filicutter. Just in case, here is some lines of enquiry:

Of course, if you want to give or ask precisions or informations, don't hesitate to contact me.

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