Currently, I am working on an Arduino and Raspberry Pi project which will have two wheels on the back to drive forward with and a servo motored fixed caster wheel at the front to control the direction. Along with this, we will have two servo motors that bring a 3D printed cage-like structure up and down in front of the robot.
We are currently looking for a 3D chassis model that will allow us to do this. P.S Our main drive wheels are 42mm wheels.