LEDBox

A modular, 3D-printable enclosure for a single row of HUB75 LED matrix panels (P1, P2, P2.5, P3, P4, P5 and similar). It prints in short sections that stack end to end on two threaded bars, with rounded end caps, a slot for a tinted acrylic front, and room inside for a power supply and controller.

It was designed for a live train departure board made from four P4 256 × 128 mm panels (a 1024 × 128 mm display), but the Fusion model is parametric: pick a panel size from a list, set how many panels you have, and the whole design resizes.

Status: early release. Only short test slices have been printed so far. A full enclosure has not yet been assembled, and several dimensions are still estimates (see Measure your panel first). Print the test slice and check it against your own panel before printing a full set.

Two versions: thick and thin

Both versions share the same layout, hardware and parameters. They differ in how much plastic they use.

	Thick	Thin
Top, bottom and back walls	2.4 mm	1.6 mm
Bar tubes	Solid square blocks	Thin round tubes
Panel mounting lips	22 mm × 3 mm	16 mm × 2.4 mm
Stiffening ribs on the back	Yes	No
Plastic per section (P4 256 × 128)	about 122 cm³	about 77 cm³
Estimated print time per section	about 4.5 hours	about 2.75 hours
Section profile (P4 256 × 128)	137.4 × 63.4 mm	135.8 × 61.4 mm
Best for	Public or knock-prone places	Faster printing, indoor use

Print times are estimates scaled from a test slice at 0.2 mm layers with a 0.4 mm nozzle.

Thick	Thin

What's in this repository

thick/
  LEDBox-thick.f3d        Fusion file, fully parametric
  stl/                    Ready-to-print parts for 4 x P4 256x128 panels
thin/
  LEDBox-thin.f3d
  stl/
images/

The STL files are for four P4 256 × 128 mm panels with the screw positions measured from one particular panel. For any other panel, or if your screw holes differ, open the Fusion file and follow Changing the design.

Parts to print

For four P4 256 × 128 panels (each panel sits on two 128 mm sections):

File	Quantity	Notes
section-vented-psu.stl	1	Vents and power supply mounting slots. Goes at the mains end.
section-plain.stl	6	Solid back with wall-mount keyholes.
section-plain-mirrored-end.stl	1	Goes at the far end.
end-cap-mains.stl	1	Opening for an IEC C14 mains inlet.
end-cap-controller.stl	1	Mounting posts and a cable opening for a controller board.
joiner-key.stl	up to 7	Optional. Slides into the top slot across each joint to keep sections aligned.
test-slice.stl	1	Optional but recommended. A short piece of a section for checking fit.

For other sizes: the number of sections is the number of panels × sections per panel. One is vented, one is the mirrored end, and the rest are plain.

Print settings

• Material: PETG or ASA. PLA softens at around 55 to 60 °C and is only suitable for test pieces.
• Supports: none.
• Sections: stand them on end. Put the end where the bar tubes run right to the face on the bed, so the short recess is at the top.
• End caps: outer end face on the bed.
• Joiner keys: flat.
• The files are exported lying down as modelled, so rotate them in your slicer.

Hardware

For four P4 256 × 128 panels:

Item	Quantity
M5 threaded bar, cut to 990 mm	2
M5 nuts and washers	4 of each
M3 screws for the panels, about 6 to 8 mm long	to suit your panel's inserts
M3 heat-set inserts (4.6 mm outside diameter type)	4 for the end caps, 4 more if you mount a controller
M3 screws, about 6 mm, for the end caps	4
3 mm acrylic sheet, 132 × 1024 mm (tinted or smoked)	1
M5 square nuts and eye bolts, for hanging	as needed
5 V power supply. The mounting slots suit a Mean Well LRS-35-5 or LRS-50-5	1
Snap-in fused IEC C14 inlet	1

For other sizes, open the Fusion file and read rod_len (bar length) and acr_h (acrylic height) from the parameter list. The acrylic is as long as the row of panels.

Assembly

1. Plug the ribbon and power cables into each panel.
2. Screw the panels to the section lips from behind. Each lip has holes for the panel's threaded inserts, and there is a screwdriver hole in the back wall directly behind each one.
3. Push the sections together and feed the two threaded bars through the tubes.
4. Fit a washer and nut on each end and tighten. The tubes stop 24 mm short at the outer ends to leave room for the nut and a socket.
5. Fit the power supply to the vented section and the controller to its end cap.
6. Slide the acrylic sheet into the front groove from one end.
7. Screw on the end caps.

To hang it: slide M5 square nuts into the slot along the top and fit eye bolts for chain or wire. To wall-mount it: use the keyholes in the back.

Safety

The enclosure can hold a mains power supply. If you fit one:

• Earth the supply, and fit its terminal cover.
• Use a fused inlet with proper strain relief on the lead.
• Keep the vents clear.
• If you are not confident with mains wiring, use an external 5 V supply and keep mains out of the enclosure. For a public place, an external supply or a metal enclosure for the mains part is the safer choice.

HUB75 panels run on 5 V only. Feeding them 12 V destroys them.

Changing the design

You don't need to know Fusion to resize LEDBox. Everything is controlled from one table of numbers.

1. Install Fusion and open the file

1. Download Autodesk Fusion from autodesk.com. A free personal-use licence is available for hobby use.
2. Download LEDBox-thick.f3d or LEDBox-thin.f3d from this repository.
3. In Fusion, choose File > Open, click Open from my computer, and select the file.

2. Open the parameter table

1. Check the box at the top left of the screen says DESIGN.
2. In the toolbar, click MODIFY, then Change Parameters at the bottom of the menu.
3. A table opens. The section called User Parameters holds every setting. Each row has a name, a value in the Expression column, and a comment saying what it does.

3. Change a value

1. Click the value in the Expression column.
2. Type the new value. Include the unit for lengths, for example 7.5 mm.
3. Press Enter. The model rebuilds, which can take a few seconds.
4. Click OK to close the table.

4. Pick your panel

Set preset to the number for your panel, and panel_count to how many panels are in your row.

preset	Pitch	Panel size (mm)	Pixels
1	P1	160 × 160	160 × 160
2	P1	320 × 160	320 × 160
3	P2	128 × 128	64 × 64
4	P2	256 × 128	128 × 64
5	P2	320 × 160	160 × 80
6	P2.5	160 × 80	64 × 32
7	P2.5	160 × 160	64 × 64
8	P2.5	320 × 160	128 × 64
9	P2.5	320 × 320	128 × 128
10	P3	192 × 96	64 × 32
11	P3	192 × 192	64 × 64
12	P3	288 × 96	96 × 32
13	P3.076	320 × 160	104 × 52
14	P4	128 × 128	32 × 32
15	P4	256 × 128	64 × 32
16	P4	256 × 256	64 × 64
17	P4	320 × 160	80 × 40
18	P5	160 × 160	32 × 32
19	P5	320 × 160	64 × 32

For a size that isn't listed, set preset to 0 and enter your panel's size in custom_w and custom_h.

Measure your panel first

The preset sets the panel's outside size only. Screw positions and thickness vary between manufacturers, so measure your own panel and enter these:

Parameter	What to measure	Current value
insert_x	Screw hole centre, from the end of the panel	7.5 mm (measured on one P4 panel)
insert_y	Screw hole centre, from the top or bottom edge	7.5 mm (measured)
insert_x2	A second screw hole, from the end of the panel	18 mm (estimate)
pin_x, pin_y	Locator pin centre, from the end and from the edge	26 mm, 9 mm (measured)
pin_d	Hole for the locator pin	3.4 mm, for a 3 mm pin
panel_thk	Panel thickness, LED face to the back of its plastic frame	15 mm (estimate)

The model puts the same hole pattern at both ends of every section, so holes your panel doesn't use are simply left empty.

Other useful settings

To change	Parameter
Printer build height, which decides whether each panel gets one section or two	bed_z
Power supply: 1 = LRS-35-5 or LRS-50-5, 2 = LRS-75-5, 3 = LRS-100-5	psu_model
Power supply mounting hole positions (estimates, check the datasheet)	psu_hole_x0, psu_hole_sx, psu_hole_y0, psu_hole_sy
Controller board hole spacing (estimate)	ctrl_sy, ctrl_sz
Mains inlet cut-out	iec_w, iec_h
Acrylic thickness	acr_thk
Wall thickness	wall, back_thk
Fit, if parts come out tight or loose	clr, sur_gap
Hole size for heat-set inserts	hs_d, hs_depth
Length of the test slice	test_len (the slice itself does not update, see below)

Some rows are calculated for you and are there to read, not edit: rod_len (bar cut length), acr_h (acrylic height), frame_h and total_depth (overall size), and psu_fits, which shows 1 if the power supply fits behind the panel and 0 if it doesn't.

5. Check the model rebuilt

Look along the timeline strip at the bottom of the screen. If any icon has turned yellow or red, a feature failed to rebuild; hover over it to see why. The usual cause is an extreme value, so undo the last change with Ctrl+Z (Cmd+Z on a Mac).

6. Export parts for printing

1. In the browser panel on the left, expand the part you want, then its Bodies folder.
2. Right-click the body and choose Save As Mesh.
3. Choose STL or 3MF, click OK, and pick where to save it.
4. Repeat for each different part. You only need one file per part type; print the plain section as many times as you need.

Things that don't update automatically

• The test slice is a fixed copy and is hidden in the file. After changing parameters, export a section and cut a short piece in your slicer instead.
• The STL files in this repository are for the default size only.

Known limits

• Tall panels: panels 256 mm or taller give a section profile bigger than a 256 mm print bed.
• Short panels: on 80 mm and 96 mm tall panels there is no room for the power supply behind the panel. Use an external supply.
• Long rows: rows longer than about 1 m need threaded bar longer than the standard 1 m length. Check rod_len.
• Larger power supplies: the LRS-75-5 and LRS-100-5 are 97 mm wide. Check psu_fits for your panel.
• End cap corners: very small panels may be too small for the default corner radius. If the end cap fails to rebuild, reduce cap_r and cap_c.

Credits

Designed in Autodesk Fusion with Claude.