One of the stranger things about the MONSTER M4SK is that it’s designed to be broken. The board can be split in two, and the halves joined with a 9-pin JST cable, allowing the eyes to be spaced differently. This is illustrated in the Fish Head guide!

Right off the bat…trouble!

The eye sockets on this mask are set too far apart even for the 100mm JST cable to reach.

Fix is simple in principle, but requires soldering finesse…

Each of the wires in the 9-pin JST cable needed to be extended. This requires:

  • Soldering iron and related paraphernalia
  • 26 or 28 gauge wire
  • Heat-shrink tubing
  • Checking your progress repeatedly

It’s not a lot of soldering, but it’s very fussy soldering. You ever solder wires and then realize you forgot to slip on the heat-shrink tubing first? There’s 18 chances to mess that up…so just work slowly and methodically.

Also, the order of the 9 wires must be maintained…if any are crossed, the second eye won’t work. It could even damage the board. Cutting and extending the wires one at a time is an option. If you decide to cut the whole cable at once, triple-check that each wire goes to the same position at both ends…and also that one of the connectors isn’t flipped 180 degrees.

I not-quite-doubled the length of the wires. This was more than I needed…but gives options in the future if I decide to pull this out and stick it in other projects.

Before anything goes in the mask, power up the board and make sure that both eyes still work.

Then disconnect the cable from both sides. There’s some cutting and gluing to be done, and we don’t want the cable getting messed up!

Another unexpected turn: originally I’d planned to use lenses with the eyes, but encountered a couple of problems…

  • The acrylic lens holders were just a tiny bit too big for the mask’s eye sockets. I could have ground down the mask or the holders, but…
  • The lenses limit the viewing angle of the screens…and with the eyes pointed somewhat outward, the effect isn’t visible from the front, where most people would be interacting.

So I decided to leave the lenses off and just use the bare screens. I’d need a way to hold them in place in the eye sockets, and also wanted to limit the amount of light that bleeds around the perimeter.

One more constraint: I’d prefer if none of this was permanent. After Halloween, I might like to take the components out and use them in the next project.

Solution to the latter was to use hot glue in key places. Hot glue can be removed using a Q-Tip dipped in rubbing alcohol. This doesn’t dissolve the glue…it cleanly breaks the bond, allowing it to be peeled away. When the time comes, this can all be dismantled and the electronics will be pristine!

Raiding my craft supply stash, I found some black craft foam (aka “fun foam”). Fashioned some frames that fit around the screens, which served multiple purposes…

  • Blocks the light bleeding out the sides of the display
  • The back side of the foam can be hot glued to the MONSTER M4SK PCB. As described above, this can be cleanly removed later. Then I can use whatever glue I want on the front side of the frames.
  • Provides a front surface that’s flush with the face of the screens…helpful for the next part…

I’m not suggesting anyone should go out and buy all these same materials. See what you have around and are comfortable working with, and improvise from that first. That goes for both materials and tools. I’m just oddly reluctant to throw anything away and have decades of accumulated craft detritus around the house. Maybe that crow mask would’ve been more fitting.

Also found in the craft hoard: black felt.

I cut two squares large enough to cover the mask’s eye sockets and then some. In the middle of each, I cut a 30mm-ish square through which the screen will be visible. Felt has some give to it, so the squares need not be perfect…you can adjust it while gluing it down to the frames.

Then I had something called Fabri-Tac glue on-hand and used that. E-6000 adhesive would also work. Once the glue dried, I glopped on some extra hot glue on the back in places around the perimeter, careful not to get any into the connector sockets.

Check that everything still works. Connect the board halves together with the cable and attach a battery or USB power.

Decide how the eyes will be positioned in the mask, make whatever marks you need to line this up again later.

After testing, disconnect all the cables again. More cutting and gluing, don’t want those getting nicked.

The felt eye squares are hot-glued back-to-front on the inside of the mask. Work slowly, one edge at a time and allowing the glue to set, so the fabric can be pulled taut as you go.

Once the glue’s all cooled down, the felt edges can be trimmed with small scissors and/or a hobby knife. Notice the wearer’s eye holes are not blocked now!

Link up the two boards with the cable again, and apply a few dabs of hot glue to keep it in place (depending on the mask or prop, zip ties can also work).

For powering the M4SK (audio will be powered separately, shown on the next page) a 500 mAh LiPo battery is slim enough to tuck behind a horn. It’s held in place with double-stick tape, wires secured with a couple dabs of hot glue. Do not hot glue the battery itself, and keep it out of spots where it could get flexed or punctured.

The 500 mAh battery gives about 3 hours run time, and takes a similar time to fully charge. If you’re planning marathon costume sessions, this cylindrical lithium-ion cell should run for closer to 12 hours. Or…if there’s space for a USB cable…even the most basic USB power banks have a ton of capacity!

Unexpected benefit of using a skull mask: if the battery runs out, when the screens go black it’s still a perfectly usable monster! The eyes and voice really step things up but aren’t a necessity for the character to work.

Bodies can be gross sometimes. We perspire continuously…salt water, basically, which is both mildly conductive and corrosive.

To keep some space between skin and electronics, I cut some pads from craft foam, held in place over the boards with double-stick foam tape.

And this is with an open-back mask! A full over-the-head mask is sweatier and has humid breath to contend with…more drastic measures might be called for: possibly even sealing the electronics with conformal coating spray, or adding a little DC fan in the snoot to bring in fresh air.

For some reason, even the simplest of costumes are always the temperature of Venus inside.

When planning how the electronics will fit, give some thought to clearances for both the USB port and audio jack. If space is tight, you can track down slim right-angle connectors for one or both.

If it’s difficult to plug and unplug the USB cable: consider just leaving it connected, and coiling up the cable in an out-of-the-way spot!

One more dry run to confirm everything still works. Try it on your head, make sure you can see OK. Doing monster “rar hands” poses is totally optional but recommended.

This guide was first published on Sep 30, 2019. It was last updated on Sep 30, 2019.
This page (Fitting the Eye Electronics) was last updated on Oct 18, 2020.