In this section I'll show how I constructed a wall-hanging canvas, with horizontal orientation, for this 4mm pitch, 64x32 pixel matrix:
The best fit I could find at Michaels was this 8.5x14 inch "traditional profile" canvas:
Behind the canvas there is enough room for the matrix, with a little to spare.
I'll use foam board and the M3 nylon standoffs to hold the matrix panel in place behind the canvas, but first it's important to understand how the power cable will be routed. It's really important for the power cable to be centered as it trails down from the canvas. If it's too off-center, the canvas will tilt sideways.
About those standoffs, I found that the shorter standoffs were about the right length to put the matrix almost touching the canvas, when the standoffs are flush with the back of the canvas.
You want the matrix panel to be very close (even touching) the canvas. If it's too far away, the images will get blurry.
This 9x12 inch foam board is a good size to start with for this canvas. I'll end up whittling a lot out of it, as you'll see in upcoming pictures.
I need to mark 6 points on the foam board that align with the 6 screw holes on the matrix panel (and the nylon standoffs). I'm not sure the best way to do this. I decided to try cutting short pieces of toothpick and laying them into the screw holes on the standoffs.
In the image above you can see 3 of the toothpick ends. The idea is to align the foam board with the canvas and press it against the toothpicks to leave an impression of the 6 mount points.
This worked well enough ... the toothpicks are much thinner than the screw holes (more like M1), so they shift around when the board is placed on top. My marks weren't perfect, but close enough, and the foam board is forgiving.
Note: in the 64x64 pixel builds I came up with a better way than toothpicks to mark the mount points. It involves taping wood screws upside down over each mount point. This eliminates the toothpick wobbling issue.
Next, I want to do the hardware work on the back of the canvas that will allow it to hang on the wall and hold the foam board with the matrix panel in place.
As the picture above shows, I'll use D-rings and hanging wire on top to allow for hanging the canvas, and 3 of the 0.25 inch offset clips on the bottom to rest the foam board on.
But there's a twist: I'm going to use 4mm spacers to raise the D-rings slightly. This will make it easier for the top of the foam board to fit under the hanging wire. I'm also using #4 screws (0.75 inch) because these fit in the Pololu spacers.
I did some measuring and marking of the foam board to determine how it will fit into the offset clips and where to place them.
The picture below shows the hanging wire and offset clips attached. You'll want to set the D-rings and hanging wire close to the top. The lower it is set, the harder it will be to slip the assembly of matrix panel, Matrix Portal and foam board into place.
Next I spent more time measuring, and then cutting the foam board. I cut away sections around the Matrix Portal and the power connector, to make room for everything.
The next picture shows the foam board screwed onto the matrix panel, with the Matrix Portal peeking out from behind.
I still needed to do a lot of cutting around the top, rounding out the corners to allow the foam board to fit under the hanging wire.
I also need to route the power cable through the bottom/middle of the foam board. I first punched a hole in the right place and then widened it to fit the cable.
Note in the second pic here how I've cut away additional foam on the bottom left to make room where the power cable plugs into the right-angle adapter.
The last thing I did is place a piece of electrical tape over the 5V and GND screw terminals to avoid accidentally touching these when the system is plugged in.
... and it works!