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Mounting the ungainly WS2812 LED test fixture seemed like a Good Idea to keep the electricity out of the usual conductive litter:

WS2812 array test fixture - rear — WS2812 array test fixture – rear

The solid model shows more details:

LED Test Fixture - solid model — LED Test Fixture – solid model

The power wires along the array edges slide into the rear (thinner) slot, with enough friction from a few gentle bends to hold the whole mess in place.

The knockoff Arduino Nano rests on the recessed ledge in the pit, with M2 screws and washers at the corners holding it down (the PCB’s built-in holes might work with 1 mm or 0-90 screws, but that’s just crazy talk). I soldered the power wires directly to the coaxial jack pins under the PCB; they snake out to the LEDs through the little trench. There should be another cutout around the USB connector for in-situ programming, although the existing code works fine.

The front (wider) slot holds a piece of translucent white acrylic to diffuse the light:

WS2812 array test fixture - front flash — WS2812 array test fixture – front flash

It’s painfully bright: a few layers of neutral density filter would be appropriate for a desk toy.

The array runs hot enough at MaxPWM = 255 to produce a gentle upward breeze.

It looks even better without the flash:

WS2812 array test fixture - front dark — WS2812 array test fixture – front dark

You’ll find many easier ways to get RGB LED panels, but that’s not the point here; I’m waiting for these things to die an unnatural death.

The OpenSCAD source code as a GitHub Gist:

	// LED Test Fixture
	// Ed Nisley KE4ZNU – February 2017

	ClampFlange = true;

	Channel = false;

	//- Extrusion parameters – must match reality!

	ThreadThick = 0.25;
	ThreadWidth = 0.40;

	function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);

	Protrusion = 0.1;

	HoleWindage = 0.2;

	//- Screw sizes

	ID = 0;
	OD = 1;
	LENGTH = 2;

	Insert = [2.8,3.5,4.0]; // M2 threaded insert
	ScrewOD = 2.0;
	WasherOD = 5.0;

	//- Component sizes

	PCBSize = [18.0,43.5,1.6]; // microcontroller PCB

	PCBClear = 2*[ThreadWidth,ThreadWidth,0]; // clearance around board

	PCBShelf = [ThreadWidth,ThreadWidth,0]; // shelf under perimeter

	PCBCavity = PCBSize – PCBShelf + [0,0,2.5]; // support shelf around bottom parts

	LEDPanel = [70,40,4.0]; // lying flat, LEDs upward
	LEDWire = [LEDPanel[0],LEDPanel[1] + 2*5.0,2.0]; // power wires along sides

	Diffuser = [LEDPanel[0],LEDPanel[1] + 2*4.0,3.5];
	echo(str("Diffuser panel: ",Diffuser));

	WallThick = 8.0;
	BaseThick = 3*ThreadThick + Insert[LENGTH] + PCBCavity[2];

	Block = [3*WallThick + PCBSize[0] + LEDPanel[2] + Diffuser[2],
	2*WallThick + IntegerMultiple(max(PCBSize[1],LEDWire[1]),5),
	BaseThick + LEDPanel[0]];

	echo(str("Block: ",Block));

	CornerRadius = 5.0;
	NumSides = 4*5;

	//- Adjust hole diameter to make the size come out right

	module PolyCyl(Dia,Height,ForceSides=0) { // based on nophead's polyholes

	Sides = (ForceSides != 0) ? ForceSides : (ceil(Dia) + 2);

	FixDia = Dia / cos(180/Sides);

	cylinder(r=(FixDia + HoleWindage)/2,h=Height,$fn=Sides);
	}

	//- Build it

	difference() {

	hull() // main block with rounded corners
	for (i=[-1,1], j=[-1,1])
	translate([i(Block[0]/2 – CornerRadius),j(Block[1]/2 – CornerRadius),,0])
	cylinder(r=CornerRadius,h=Block[2],$fn=NumSides);

	translate([2*WallThick + PCBSize[0] – Block[0],
	0,
	(Block[2]/2 + BaseThick)])
	cube(Block + [0,2*Protrusion,0],center=true); // cut out over PCB

	translate([WallThick + (PCBSize + PCBClear)[0]/2 – Block[0]/2,
	0,
	0]) {
	translate([0,0,(BaseThick + (Protrusion – PCBSize[2])/2)])
	cube(PCBSize + PCBClear + [0,0,Protrusion],center=true); // PCB recess

	translate([0,0,(BaseThick + (Protrusion – PCBCavity[2])/2)])
	cube(PCBCavity + [0,0,Protrusion],center=true); // cavity under PCB

	translate([PCBSize[0]/2 + WallThick/2 – Protrusion/2,PCBSize[1]/2 – 15/2,BaseThick – PCBCavity[2]/2 + Protrusion/2])
	cube([WallThick + PCBShelf[0] + Protrusion,
	15,PCBCavity[2] + Protrusion],center=true); // wiring cutout

	for (i=[-1,1], j=[-1,1]) // screw inserts
	translate([i(PCBSize[0] + ScrewOD)/2,j(PCBSize[1] + ScrewOD)/2,-Protrusion])
	rotate(180/(2*6))
	PolyCyl(Insert[OD],BaseThick + 2*Protrusion,6);
	}

	resize([2*Block[0],0,LEDPanel[0] + Protrusion]) // LED panel outline
	translate([0,0,BaseThick])
	rotate([0,-90,0])
	translate([(LEDPanel[0] + Protrusion)/2,0,0])
	cube(LEDPanel + [Protrusion,0,0],center=true);

	translate([-Block[0]/2 + 2WallThick + PCBSize[0] + LEDWire[2]/2 + 5ThreadWidth,
	0,BaseThick]) // LED wiring recess
	rotate([0,-90,0])
	translate([(LEDWire[0] + Protrusion)/2,0,0])
	cube(LEDWire + [Protrusion,0,0],center=true);


	translate([Block[0]/2 – Diffuser[2]/2 – 5*ThreadWidth,0,BaseThick]) // diffuser
	rotate([0,-90,0])
	translate([(Diffuser[0] + Protrusion)/2,0,0])
	cube(Diffuser + [Protrusion,0,0],center=true);
	}

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