A robotic project aimed at my 12 year old students. The MR - 1 has an Arduino/Genuino brain.

It prints out in a single piece and can be printed on a relatively small print bed.

I have on youtube a series of videos on how to program it:
https://www.youtube.com/watch?v=qd-gISNsYGI&list=PLvLlImx6xJJzP7LY6nLryig5ywhhM8PiK

I buy my parts from Little Bird Electronics in Australia.
The parts needed are:
An Arduino/Genuino - I use the Arduino 101
2 x motors: https://littlebirdelectronics.com.au/products/dc-geared-motor-with-rubber-wheel
HC-SR04 Ultrasonic Sensor: https://littlebirdelectronics.com.au/products/ultrasonic-ranging-module-hc-sr04
Motor Controller: https://littlebirdelectronics.com.au/products/l298-dual-h-bridge-motor-driver

Up!

Up Plus2

Yes

Yes

0.15mm

Tight

My Up! Plus 2 printed this out nicely. The supports took some time to remove but did not require too much effort. If you use the genuine Up! Premium White filament it will come off very easily. I heated the room that the printer was in to 30 degrees C and had only very minor warp issues.

I made this on 123D Design using the techiques outlined in my 3D Printed Robotics series on Youtube.
https://www.youtube.com/watch?v=UFQspkRmJrQ&list=PLvLlImx6xJJwpTg7SSNuwDXm3DiqQWjOs