This is a simple protoboard DIP daughter board for when you need something more durable than a breadboard. The protoboard holes are connected where indicated by exposed copper, for easier wire routing and soldering.
The KiCad schematic and layout are available at the Github repo. The project is released as open hardware under the CERN v1.2 Open Hardware license.
This project was created using the CHIP DIP KiCad template from Wickerlib.
Buying bare boards from OSH Park costs $17.50 for a set of three. You’ll want to buy the headers separately.
For a non-stackable version, you can just use two standard 0.1” (2.54mm) pitch 1x40 headers, each snapped in half.
For a stackable version, you can use two of these extra-tall 2x20 female headers from Adafruit. The connectors are from the Samtec SSQ family so you could shop around for other distributors, but Adafruit has by far the best price for this particular component.