In a first attempt at this project I’d tried installing the MONSTER M4SK board under the brim of the hat. This might work for you, but I found it presented a couple of problems…

First, the screens used on the MONSTER M4SK bleed a fair bit of light around the perimeter. For the Pepper’s ghost effect to really work we want the eye graphics to be the only source of light.

This can be fixed by making a stencil from vinyl, craft foam or construction paper, with cutout circles for the eyes.

Second, the effect looked great head-on, but any amount of parallax had the cartoon eyes projected about half an inch in front of my own eyes. We can fix this!

The trick is to position the screens at the same distance from the glass as one’s own eyes…they’ll then appear to occupy the same space. I’ll just move the board up above the brim of the hat, with cut-outs for the eyes.

Every hat and head and how it fits will be different! So, before you go cutting or gluing anything, do some test mock-ups first by holding things in place manually, or with bits of masking tape or whatever you can improvise. Check in a mirror or with a friend’s help. Figure out the ideal distance…under brim, over brim, how much extra space…then we can proceed.

If planning to make a stencil or eye holes in your hat, here’s a template you can download and print:

Before you cut into anything, be absolutely certain the template prints actual size! Hold the MONSTER M4SK board over it to confirm.

If you don’t have a printer you can still make your own template manually: the eye holes are 30 millimeter circles, spaced 63.6 mm center-to-center (or 33.6 mm inner edge-to-edge), and the minimum headroom above the circles is 13.5 millimeters.

Cut out the paper template carefully with a hobby knife or scissors, and do one last size check over the MONSTER M4SK before committing to the hat…

Trace the eye holes onto the hat with a contrasting pen or pencil. Silver Sharpie markers are a godsend, or colored pencil may work just fine.

The TOP EDGE of the MONSTER M4SK faces “in,” toward the forehead.

Remember, cutting the hat is only required if you’ve determined the best placement for the MONSTER M4SK is over the brim. If going under the brim, leave the hat alone, and the template is still useful for making a light-blocking stencil.

Carefully cut the eye holes using a sharp hobby knife. Better to go a little small than too large…you have more control to make adjustments with additional passes.

Since this hat is 35% polyester fiber, frayed edges could be cleaned up by briefly passing a lighter underneath. Please don’t set your hat or anything else on fire.

Hold the MONSTER M4SK in place, flip the hat and see how it looks.

If you cut the holes too big, don’t panic! You can still fashion a stencil from vinyl or construction paper or whatnot, and keep it held between the board and hat.

The board is best held in place with some hot glue. Or you can try poking extra holes in the hat and using M3 screws and nuts, but I found this made unsightly puckers in the hat brim.

On the next page I show covering up the board with some fabric to hide it.

TO DISMANTLE THE PROJECT LATER, or to reposition the board, hot glue can be removed using a Q-Tip dipped in rubbing alcohol. This doesn’t dissolve the glue, it just seeps between the glue and PCB and cleanly breaks the bond. This won’t get any glue out of the fibers of the hat though.

Before you bolt or glue the board in place…at some point you’ll want to remove the clear plastic stickers that protect the screens during PCB assembly. They’ve done their job and just make the image blurry now.

For holding the glass now…you can use the same 3D-printed clip doodad shown on the prior page…but not clipped to the PCB. It can be affixed under the brim of the hat using hot glue or E6000.

This guide was first published on Sep 10, 2019. It was last updated on Sep 10, 2019.

This page (Assembly Part 2) was last updated on Sep 03, 2019.

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