You should be familiar with the basic setup of the M4 Eyes project based on the most excellent Adafruit MONSTER M4SK Guide Quickstart. Before you proceed with making your own eye pattern texture maps, be sure you've got the M4Eyes.UF2 working properly using the default Hazel eyes graphics.
There are a few different ways to add eyes to your dummy. Depending on the dummy you're using, and the size of their head, there may be more or less space for adding the eyes internally to the head. This is probably the best looking, most convincing approach, but not always possible.
You may also not be prepared to cut out the eyes and open the skull of your dummy, which is totally understandable! In these cases, there are a couple of ways to add the MONSTER M4SK externally like a mask or comically oversized glasses.
Let's take a look at these different techniques.
The most straightforward way to add eyes to your dummy is to add an elastic band to the unaltered M4SK.
This approach can look more comical, with the eye size exaggeration provided by the convex lenses. We'll use the frames from an old pair of glasses to bring it all together and to mount it on the dummy's head.
Starting with an old pair of glasses (check a thrift shop if you don't have any laying around), pop out the original lenses, we won't be using them.
Next, trace the M4SK shape onto a piece of black cardstock. We'll use this to cover the glossy acrylic lens holders and the M4SK board graphics.
Also mark the mounting hole locations -- this is easier done with a thin tipped, long reach marker, or simply poke holes using an awl or thin screwdriver.
Cut out the cardstock using a hobby knife or scissors.
Next, we will mark the lens cutouts. The easiest way to get this alignment correct is to lay the cardstock onto the M4SK and then place the two acrylic lens holders on top, pushing the mounting screws all the way through.
Mark the two circles for the lens cutouts, and then disassemble it all to cut out the circles.
M4SK Sandwich Assembly
I found the easiest way to assemble the sandwich is upside down on the worktop in this order:
Connect the M4SK assembly to the glasses frames using four small zip ties as shown here.
If necessary, add some elastic to the arms of the glasses as shown.
Time for surgery, Slappy. Sorry! This is the most invasive method of adding eyes to your dummy, but it also looks the most natural. You may want to practice on a thrift store doll first!
Original Eye Removal
If your dummy has static, molded and painted eyes, you can remove them with a sharp hobby knife. Just go slowly and carefully.
Remember, it's easier to remove material than to add it back, so start small if you're unsure how large to make the holes. Here I started with just the eyes and left the lids alone.
Some ventriloquist dummies have easy access to the skull interior from inside the chest cavity. If not, you may need to either remove the head from the body and access it from the neck, or create an opening in the back of the skull in order to mount the M4SK.
Carefully create an incision in the base of the hairline using a sharp hobby knife. I sliced along the hairline and up above the ears, heading toward the center, but leaving a flap attached to form a kind of hinge.
If your dummy's head is large enough, you may be able to mount the MONSTER M4SK as is inside of the head now! A few spots of high temperature hot glue work very well -- just align the screens with the centers of the eyes and hold in place while the glue cools.
If the spacing isn't right for this, you can now separate the M4SK in to two halves.
Follow the instructions in this guide to separate the MONSTER M4SK halves and join them with the 9-pin JST SH cable.
Now, you can fit the eyes closer together, which works well for the average ventriloquist dummy.
The trickiest part can be mounting the two halves to they are centered and secured. You can try different things, including Velcro, hot glue, and gaffer's tape. For Slappy, I decided to create four attachment "posts" using zip ties and hot glue.
Using hot glue, attach four zip ties inside the mask like four posts. You can experiment with position based on the M4SK halves.
Slide each M4SK half down two of the zip ties, threaded through two mounting holes until they're properly positioned.
You can now secure the boards using four more zip ties, slid over the existing ones as shown.
Once you've tightened them down you can snip off the excess lengths with diagonal cutters or scissors.
Your dummy has now come to life! You'll want to keep the board accessible for charging the battery and uploading new code to the M4SK, as well as using the on-off switch.
You can use adhesive Velcro to make a small latch for opening and closing the skull flap for this purpose.
To better blend the seam, you can use a black permanent marker to color in the edge of the skull flap.