This is a 1/28 scale version of the standard 1/16 scale DIYRoboCar Donkey vehicle. It originated from work Tawn Kramer did in Fusion360 and I wrapped it in openSCAD and added a few elements to it like mounts on the front for 1/2 of a PCA9685 PWM driver board.
I've included the SVG file if you want to laser cut the base platform instead of 3D printing it. I made this in 1/8" plywood and use a little etching to make the pin areas thin enough for pin access to the vehicle pin mounting holes.
I downloaded the Fusion 360 project in the STEP file format and then imported it into FreeCAD. From there I selected the components and exported those STL files. After that I created the OpenSCAD design where I imported the STL files, rotated and moved them around and then manipulated by adding(union) and subtracting(difference) elements.
Tawn Kramer's design can be found here - https://myhub.autodesk360.com/ue2b357b5/g/shares/SHabee1QT1a327cf2b7a85223ca5ffd6ed3b