Foam Cutting with Stencils

The Helmet

I cut a piece of foam with a stencil, and it turned out terrible! So I tried again, and it turned out better…

A member of Milwaukee Makerspace loaned me his Proxxon Hotwire Cutter Thermocut to cut some foam. If you remember one of my previous foam cutting experiences using a drill press, that worked ok, but I wanted to try another method, the hot wire foam cutter actually designed to cut foam.


I started with not one, but two stencils, with the idea being I’d put them on the top and bottom of the piece, lined up with each other.


Why two stencils? when I tried to just use a top stencil with the wire cutter, the wire flexed a bit and I got not-straight lines.

Taping to foam

I attached the top of the “stencil placement guide” to the top of the foam with tape…

Taping to foam

…and then attached the bottom to the bottom, lining them up with the corner so they’d be in alignment with each other.

Spray glue

I then spray glued the actual pieces I wanted to stick to the foam with spray glue (using our spray booth!) Note that one piece is flipped upside down and one isn’t, so they match each holder.

Put it on the foam

Here’s the top piece glued into place…

Put it on the foam

…and the bottom piece glued into place.

Stencil on foam

Once glued in place I remove the top stencil holder…

Stencil on foam

…and the bottom stencil holder. Now we can cut. Hot wire goes through foam so fast I didn’t even get a photo!

Stencil on foam

Here’s the helmet cut out of foam. Top view…

Stencil on foam

…and bottom view. Yes, there are some rough spots, but the wire stayed pretty well aligned thanks to the top and bottom stencils. You just need to glide the wire along the paper’s edge. Much easier than trying to freehand a line drawn on the foam, and better results too!

You may have noticed a hole show up in the helmet. The reason for that was to feed the wire through to cut out the middle, but I forgot the wire was on a spool, so… bigger hole!


I cut a hole just large enough to fit the spool through…


…and once it was through, reattached it to the cutter so I could cut out the middle piece.


The middle piece came out pretty good… Now that’s a helmet!


A few of the cuts are a bit rough, but some sandpaper makes light work of them.


Ahh, now here you can see the terrible results of only using a top stencil from my previous attempt. The wire tended to cut deeper into the bottom of the foam where there was no stencil to guide it.


Our new improved helmet cut with top and bottom guides is much better. And hey, now it’s ready to be cast in aluminum!


While the Proxxon is nice, there are a lot of DIY foam cutters that can be built with scrap materials. Ultimately though, I think a CNC cutter would be cool. Just add an XY table and away you go!


Cutting with the Silhouette Cameo


I (briefly) mentioned the Silhouette Cameo cutter in a previous post, but I thought I should dedicate a full post to it and how I use it.

I treat the Silhouette Cameo like a CNC machine, and have a similar workflow to the one I use with the laser cutters at Milwaukee Makerspace. I know the Silhouette folks have the Silhouette Online Store where you can buy ready-made shapes to cut, but we’re makers, and we make our own things, so I use Inkscape and if I need a shape I hit up OpenClipArt and find what I need. (Note: All the art on is in the Public Domain, which means you can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission, because permission has already been granted.)

My daughter wanted a kangaroo cut out of vinyl to give to her friend, so I found a kangaroo on OpenClipArt and cut it for her.

Kangaroo in Inkscape

The files on OpenClipArt are in SVG format, which are perfect for Inkscape, as they are the native file format, meaning you can open them right up with no conversion necessary. Here’s our kangaroo in Inkscape. (I won’t go too deep into vector artwork, but if you don’t know, you can scale up and down vector art with no loss of quality, as it’s comprised of lines defined by fancy math, and not a set grid of pixels like raster art, or a digital photo.)

Resizing in Inkscape

The final piece was to be about 4 inches wide, or roughly 100 mm. (You can work in Imperial or Metric measurements in Silhouette Studio—and Inkscape—so use whatever you’re comfortable with.)

I resized the document to 4″ x 3″ using the Document Properties dialog box…

Resizing the Kangaroo in Inkscape

You can see our kangaroo will need to be shrunk to fit within the confines of the document…

Resizing the Kangaroo in Inkscape

Resizing something proportionally in Inkscape is pretty simple. Use the arrow tool, hold down the control key, and move one of the corner points. There’s actually more than one way to resize things, but for eyeballing it, this will work.

Resizing in Inkscape

OK, once we have our artwork the proper size, we can save it (still in SVG format) and the we’ll need to save it as a DXF file so we can get it into Silhouette Studio.

Select ‘Save a Copy…” from the file menu…

Kangaroo in Inkscape

Select “Desktop Cutting Plotter” from the file type menu. (You’ll see it has ‘dxf’ in the name as well, and you may have other DXF options depending on your Inkscape installation, but this one works for me.)

Kangaroo in Inkscape

You shouldn’t need to check either checkbox, just leave the options as they are.

I should note that when exporting DXF files for other purposes, such as loading into OpenSCAD for 3D modeling, we would have needed to convert all the curves to straight lines before creating our DXF file, but the Silhouette Studio software will work just fine without this step.

Kangaroo in Silhouette Studio

OK! We now create a new file in Silhouette Studio, and you can just drag and drop your DXF file onto the canvas. Once it’s there you can resize it as desired. (Wait, didn’t we size it in Inkscape already? Yes we did, that was just my way of teaching you one more thing about Inkscape. You’re welcome!)

Once you’ve got your artwork sized and positioned, you can do your cutting with the appropriate settings.

Kangaroo cut from vinyl

Here’s our final version of a white kangaroo, which my daughter gave to her friend. Hooray for CNC machines that can cut vinyl!

(You may be saying, “Hey! That kangaroo looks larger than the 4″ x 3” one you mentioned above! And yes, it is. After cutting one, a much larger version was requested, so that’s the one you see here.)


Pac-Man Cookies

Cookie Cutters

Since I’ve been playing with the MakerBot at the Milwaukee Makerspace, I figured that I should print something useful, and what’s more useful than cookie cutters!

I got the idea from the GuruBlog CookieCutter-Editor. I ended up making the Pac-Man shape, which is the exact opposite of complicated. (Yeah, I’m saying it’s really simple.) I really just did the Pac-Man shape as a test, and after I posted it, Alex asked about the ghosts, so at that point I figured I had a bit more work to do…

Since I’m still dabbling in 3D modeling, and haven’t really nailed down a workflow yet, I decided to try something besides the CookieCutter-Editor. I ended up drawing the ghost in Photoshop, and then bringing it into Inkscape to trace it. I then followed this Inkscape to OpenSCAD dxf tutorial to convert the SVG into a DXF file, which I then exported and brought into OpenSCAD to extrude into a 3D model.

Printed Cookie Cutters

The Pac-Man shape from the CookieCutter-Editor had a wider edge on one end, which is what a cookie cutter should have. (You can see this in the 3D wireframe in the top image.) The ghost shape does not have this wider edge, because I don’t know how to create one yet! I solved this issue by printing the shape with a raft, which you can see in the photo of the printed cutter. It’s not the prettiest cookie cutter, but it certainly did work.

Pac-Man Cookies

And here’s our final product, the Pac-Man (and ghosts) cookies! My oldest daughter Emma did the hard work here. She made the cookie dough, used the cutters, baked the cookies, and frosted them. I was basically the “Technical Advisor” and showed her what colors to use, etc. She wasn’t 100% pleased with the outcome, mainly because she had to tweak the coloring and improvise a bit (Pac-Man is actually lemon-flavored) but she’s a bit of a perfectionist in the kitchen. :)

We’ll probably make more of these for BarCampMilwaukee6, and may throw a few more shapes into the mix if I get a bit time with the MakerBot before then.