office buildings to diffuse fluorescent lights. They’re readily
available at stores like Home Depot in 2’ x 4’ panels
(which is why my display is 2’ x 3’).
If you want a larger display, you’ll need to use either
more than one diffuser or a frosted piece of plastic. Craft
stores sell spray paints that will frost most anything. Files
for the eye and mouth segments are available at the article
link to use as a reference pattern.
Drawing the Face
Referring to Figure 5, start the face by drawing an
ellipse on the MDF backing. How do you do this on a large
surface area? Math! In order to draw a circle, you’d need a
pencil, a piece of string, and an anchor. Put the anchor
where you want the center or focus of the circle, tie the
string between the anchor and the pencil, then trace the
circle by stretching the string as far as it will go. When the
pencil goes around a full 360 degrees, you’ll have a perfect
circle. So, how do you do this with an ellipse?
If you remember your math (if you don’t, check
Wikipedia), an ellipse has two focal points where a circle
only has one. You’ll need two anchors to draw an ellipse;
food cans work fine. Use the string to tie a loop and place
it loosely around both anchors. If you stretch the string
with the pencil and go around 360 degrees, you’ll have a
perfect ellipse. Move the anchors to change the shape of
the ellipse, and increase the length of the string to
increase the size.
If you want a more natural face, sketch the opening
for the eyes at about the center of your display. Make the
opening of the eyes large so you have enough room to
incorporate all of the segments for the eye animations.
The mouth will be centered between the eyes and edge of
your display. Again, make the mouth large enough to be
open with an “ah” shape. You can also download a
template that I used to make the face from the article link
or pumpkinfx.com. Print it out, then trace the design onto
the MDF using carbon tracing paper.
Building the Face Front
Use a drill to make pilot holes in the eyes and mouth
on the MDF panel, then use a jigsaw to cut out the shape
of your face. Use sandpaper to smooth out any rough
spots. Cut out the shape for the diffuser next. The outline
of the diffuser should match the MDF panel you just cut,
and you can use this panel as a template. Clamp the
diffuser and MDF panel together while you make the cuts.
Go slowly in order to prevent chipping on the diffuser.
Finish the diffuser by painting on the smooth side with
opaque glass paint which is available at a craft store. You
may need more than one coat as painting smooth
surfaces is a bit of a challenge.
Building the Light Box
For my light box, I’m using a Sterilite 67 quart
underbed box (UPC 073149189585). This works well for
a small display because all of the electronics are contained
in one box. For a bigger display, you can split the light box
into three separate units. I removed the wheels on my
plastic box and painted the outside with black spray paint.
The segments for the animated display need to be
distinct from each other. This means that the light from
one segment shouldn’t bleed into another segment. In
order to separate the lights, we’ll need to use two of the
most magical items used for crafting.
The first is cardboard. It’s cheap, sturdy, lightweight,
readily available, easy to cut, forgiving if you make a
mistake, and accepts paint extremely well. The only
46 September 2014
FIGURE 4. Side
view of face
front and light
Video of Pumpkin FX in action
on Xbox Music
Preston Blair Mouth Shapes
by the SD Association
Falcon Pi Player Tutorials
by Alan Dahl
"How to protect circuits from
reversed voltage polarity!"
"Surface Mount Soldering 101"