This is a custom tray for mounting an Arduino Uno, a prototyping breadboard, and two LM2596 DC-DC Buck converter modules (or similarly sized prototyping PCBs). It is specifically sized to fit inside the plastic box which came with an "Uno R3 starter kit" which I had ordered on eBay. It is designed with an open end to allow for the use of longer prototyping breadboards. There is also an area where parts can be placed temporarily while prototyping, so they don't get lost.

All mounting holes will accommodate m2.5 mounting screws up to 8 mm in length. An Arduino will usually be mounted with m3 screws, but due to some interference with the top of the pan-head screws and board headers, I chose to use m2.5 screws instead, and moved one of the Arduino mounting holes to a 0.5mm offset position to avoid interference. This also means I am using the same size mounting screws for the Arduino as I am using with the LM2596 DC-DC Buck converter modules.

Dimensions: 170mm x 83mm x 25mm

Revision history:
• v1: First draft.
• v2: Changed Arduino mounting holes to m2.5 and offset one hole to avoid interference with a header. Also enlarged the overall size, and added mounting points for a 2nd buck converter.
• v3: Added a through-hole path for an optional power-input cable between the Arduino and the Breadboard. Also added a small handle which can also be used for wire management.

Creality

Ender 3

No

No

0.12mm

20%

I designed this in Fusion 360 using mm as the design units. I found Arduino and LM2596 module dimensions and mounting hole locations online; These parts seem to have been originally designed using inch units, so I put those inch units directly into the design, to avoid conversion errors. Some dimensions were also physically measured using digital calipers.
Fit clearance tolerances have also been added into the design, as appropriate.

An exported Fusion 360 (.f3d) file, a STEP file, and an IGES file are also provided for anyone who wants to modify / remix this is.