![Modular ITX/DTX/mATX/ATX/SSI-EEB/SSI-CEB/EATX/XL-ATX mainboard frame/tray [Updated 2026-07-19]](/api/img?u=https%3A%2F%2Fmedia.printables.com%2Fmedia%2Fprints%2F35720%2Fimages%2F1199286_159f781c-d9e2-4896-be13-5668e22d36a3%2Featxv3.jpg)
Introduction
This is a simple PC mainboard frame/tray system intended for open-air or custom enclosure PC builds. The intent is to support a broad variety of mainboards from iTX to so-called EATX with modules that fasten together with M4 nuts and bolts.
Version log
v3.11 (2026-07-19)
Corrected 0.5mm step/discontinuity cosmetic issue on a portion of itx and other parts (thanks to @nanuk)
Added back missing standoff hole to matx-full-extension variants (thanks to @Alterix)
Added "narrow" version of mATX-full-extension for certain mATX mainboards with two ram slots that are just a few cm wider than ITX. (thanks to @Alterix for the idea)
v3.1 (2026-01-17)
M4 fastener holes increased from 4mm to 4.25mm diameter to ease fitment
add "I/O shield" text to indicate orientation of mainboard
added back single piece matx for larger printers like Core 1, P1S, U1, etc.
added 1.85mm "trimmed" versions of "EATX" parts to correct standoff locations for some boards
added fastening holes for upcoming I/O shield and PCIe card holder parts
v3
matx1 piece adds a protrusion for an optional standoff location
itx and atx parts add optional standoff locations for SSI mainboards
re-uploaded files with “medium” detail level to reduce file size
v2
added missing standoff hole on atx2
all standoff and frame holes same size
add 0.25mm filets to all edges
v1.3
matx updated to be 4 pieces instead of 1 to print on smaller printers
v1.2
added SSI mounting holes
recessed landing pads for frame mounting screws
added legible part name inscriptions
v1.1
initial design concept
Required parts
mini-ITX/mini-DTX/ITX
1 part (itx.stl)
4 mainboard standoffs
optional: 4 screws to secure frame to other components
DTX
2 parts (itx.stl & dtx.stl)
2 nuts/bolts + 4 washers to fasten parts together
4-6 mainboard standoffs
optional: 4-6 screws to secure frame to other components
micro-ATX (mATX)
4 parts (itx.stl, dtx.stl, matx1.stl, matx2.stl)
4 nuts/bolts + 8 washers to fasten parts together
5-8 mainboard standoffs
optional: 4-6 screws to secure frame to other components
micro-ATX (mATX) alternate for larger printers
1 part (matx-full.stl or matx-full-extension.stl or matx-full-extension-narrow.stl)
5-8 mainboard standoffs
optional: 4-6 screws to secure frame to other components
ATX
4 parts (itx.stl, dtx.stl, atx1.stl, atx2.stl)
5 nuts/bolts + 10 washers to fasten parts together
6-10 mainboard standoffs
optional: 6-8 screws to secure frame to other components
EATX (SSI-CEB/SSI-EEB/XL-ATX)
6 parts (itx.stl, dtx.stl, atx1.stl, atx2.stl, eatx1.stl, eatx2.stl)
7 nuts/bolts + 14 washers to fasten parts together
8-15 mainboard standoffs
optional: 8-12 screws to secure frame to other components
Fasteners
M4 nuts, bolts, and washers to secure frame pieces together
M3x6x6 mainboard standoffs and m3 screws to secure mainboard to frame
When fastening the frame to a table or other components use washers to spread the load!
Exterior measurements of the parts
itx: 170.330mm x 171.600mm
dtx: 170.330 x 72.240
matx1: 171.6 x 45.720
matx2: 72.240 x 45.720
matx-full: 216.050 x 243.840 (243.840 x 243.840 extended version)
atx1: 134.470 x 171.600
atx2: 134.470 x 45.720
eatx1: 134.470 x 86.360 (134.470 x 84.5 trimmed version)
eatx2: 170.330 x 86.360 (170.330 x 84.5 trimmed version)
Notes
Accepts 6-32 and M3 motherboard standoffs. Holes are 3.25mm in diameter gradually tapering to ~2.3mm to grip the standoffs. This may be adjusted in future revisions.
Extra holes are added to accommodate SSI-style boards in addition to ATX style boards
10mm z-height - combined with ~6mm high mainboard standoffs provides ample clearance for PCIe card tabs
Can use a variety of fasteners to attach the frame parts together and/or secure the frame to a surface or custom chassis. Fasteners can be up to ~4mm in diameter. Washers should be used to spread the load against the plastic to avoid cracking
PETG recommended for durability/flexibility, but PLA is OK. For environments where air temperature exceeds 60°C, ABS/ASA is probably a better long-term material.
Most 3D-printed materials are non-conductive and can build-up static charge. I doubt its necessary, but to mitigate static, ~28awg wires terminated with spade connectors can be run between a few motherboard standoffs and then grounded to the power supply.
References for mainboard sizes and standoff locations
https://web.archive.org/web/20160817033942/http://www.formfactors.org/developer/specs/atx2_1.pdf
https://www.snia.org/sites/default/files/SSIF/2018-05-31/SSI%20EEB%202011%201.0.1.pdf
https://digitallibrary.intel.com/content/dam/ccl/public/600565-btx-specification-update-rev1p1.pdf
https://linustechtips.com/main/topic/812415-ee-atx-standoff-locations/
https://www.gamersnexus.net/guides/3566-e-atx-is-a-lie-vs-xl-atx-eeb-ceb
https://hardwarecanucks.com/forum/threads/lets-go-team.12383/page-432#post-527475
To-do
Design add-on parts to hold a bolt-on I/O shield and PCIe cards
Modular ITX/DTX/mATX/ATX/SSI-EEB/SSI-CEB/EATX/XL-ATX mainboard frame/tray [Updated 2026-07-19]
by DockGuy · original on Printables ↗
Gadgets / Computers
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Print profiles
mainboard - matx2-v3.stl
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mainboard - eatx2-v3.stl
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mainboard - eatx1-v3.stl
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mainboard - atx1-v3.stl
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mainboard - dtx-v3.stl
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mainboard - itx-v3.stl
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mainboard - atx2-v3.stl
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mainboard - matx1-v3.stl
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mainboard - atx1 v31.stl
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mainboard - matx2 v31.stl
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mainboard - eatx2-trimmed v31.stl
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mainboard - atx2 v31.stl
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mainboard - dtx v31.stl
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mainboard - eatx1-trimmed v31.stl
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mainboard - eatx2-original v31.stl
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mainboard - eatx1-original v31.stl
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mainboard - itx - v311.stlDEFAULT
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mainboard - matx1 - v311.stl
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mainboard - matx1-extension -v311.stl
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mainboard - matx-full-extension -v311.stl
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mainboard - matx-full -v311.stl
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mainboard - matx-full-extension-narrow v311.stl
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