Fixing Breadboards for Wide Microcontrollers – Pico & ESP32 Edition

Many modern microcontroller boards such as the Raspberry Pi Pico or ESP32 development boards are too wide for standard breadboards. When plugged directly into a regular breadboard, they cover multiple contact points — with the Pico only two usable holes per pin remain, and with the ESP32 there is no space at all on either side. This makes prototyping inconvenient or even impossible.

In this project, a standard breadboard is modified to perfectly accommodate these wider boards. The original metal spring contacts are removed and reused in a newly designed 3D-printed breadboard body. The new board provides the same 63×5 contact layout as a full-size commercial breadboard, and includes two vertical power rails on both sides.

The microcontroller is inserted into the inner rows, leaving four freely accessible holes per pin for jumper wires and additional components — ideal for prototyping and experimentation.

Two variants are provided:

1. Version 1: Raspberry Pi Pico (pin spacing 7×2.54 mm = 17.78 mm)
2. Version 2: ESP32 development board (pin spacing 10×2.54 mm = 25.4 mm)

All design files are included in the GitHub repository: original Autodesk Fusion source files, STL models, and 3MF print files for direct use with Bambu Studio.

This project is inspired by a MAKE Advent Calendar 2025 Tinkercad model, but expanded to a full-length breadboard with 63 contact rows and complete power rails.

Modern microcontroller boards such as the Raspberry Pi Pico or ESP32 Dev Board are wider than classic DIP ICs. When you plug a Pico into a standard solderless breadboard, it covers several hole positions and only two usable holes per pin remain. With an ESP32 Dev Board the situation is even worse: there is no usable space on either side, making normal prototyping impossible unless two breadboards are placed next to each other.

1. This is inconvenient and wastes space. Breadboards have not really evolved for modern MCU board form factors, so this project fixes that.

The idea behind this project is to take the metal spring contacts from a regular commercial breadboard and reuse them in a custom 3D-printed breadboard body. The new body maintains the full 63×5 contact row layout found in classic full-length breadboards, and includes two vertical power rails on the left and right just like the original.

Two versions are available:

1. Pico version: fits Raspberry Pi Pico (7×2.54 mm pin spacing)
2. ESP32 version: fits ESP32 Dev Board (10×2.54 mm pin spacing)

When the microcontroller is installed, it occupies the inner contacts of the 5-pin groups, leaving four free holes per pinfor jumper wires and components. This solves the prototyping space issue without requiring two breadboards.

List of what users need:

Materials:

1. 1× standard breadboard (for harvesting contacts)
2. 3D-printed breadboard body (Pico or ESP32)
3. 3D-printed bottom plate
4. Optional: 2× M2×7 screws + nuts (for mechanical fastening)
5. Glue (alternative to screws)

Tools:

1. Cutter or hobby knife (to remove adhesive tape)
2. Tweezers or needle-nose pliers
3. Screwdriver
4. 3D printer OR access to one

Turn the commercial breadboard upside down and remove the adhesive tape from the bottom. Underneath you will find the metal spring contacts. Carefully lift them out using tweezers or small pliers. Remove the 5-pin horizontal contacts for the main area and also remove the vertical power rail contacts on both sides. Keep the two groups separate and straighten any bent contacts if necessary.

Print quality and tolerances are critical for this project. The plastic webs between the individual contact holes are only about 0.5 mm wide, and the holes for the metal contacts have a diameter of less than 1 mm. If the print is not clean, the contacts will either not fit at all or sit too loosely.

It took several test prints to dial in the tolerances so that the contacts slide in with a firm but non-destructive fit. Make sure your printer is well calibrated and that the flow/extrusion parameters for your filament are tuned for accurate small features. A slightly over-extruding setup can easily close or distort the tiny holes.

I am using a Bambu Lab X1C, which automatically optimizes many parameters and helps achieve reliable results on these fine structures. With other printers, you may need to experiment with:

1. flow / extrusion multiplier
2. print temperature
3. speed (slower can help with detail)
4. horizontal expansion or hole compensation settings

Once you are satisfied with the print quality, clean up any small strings or blobs and test-fit a few contacts to make sure they go in straight and the structure is not weakened.

Insert the 5-pin spring contacts row by row into the new breadboard body. Make sure each row sits flush and level. After the horizontal rows are installed, insert the power rail contacts on the left and right side. The fit should be snug and should hold the contacts in place without any hammering or excessive force.

Align the bottom plate with the main body and secure it. There are two ways to do this:

1. With screws: insert and tighten the two M2×7 screws until the plate is held firmly in place. Do not overtighten.
2. With glue: apply a thin bead of adhesive to the mating surface, press the plate in position, and allow it to cure.

Both methods work and prevent the contacts from sliding out during use.

Insert the Raspberry Pi Pico or ESP32 Dev Board into the inner contact rows. Unlike with a standard breadboard, there are now four accessible holes per pin available on the outer side for jumper wires and additional components. This restores usable prototyping space for sensors, power wiring, debugging signals, and more.

Use the custom breadboard just like any other solderless breadboard. Plug in jumper wires, add resistors or capacitors, power the board through the side rails, and connect external modules or breakout boards. The layout remains compatible with common prototyping workflows, but finally fits wider microcontrollers properly.

The original Fusion 360 CAD files, STL files, 3MF print files, and assembly photos are provided in the GitHub repository:

https://github.com/lhm0/wide-mcu-breadboard

This makes it easy to remix the design for other microcontroller boards or modify mechanical details.