This short Instructable will show you how to create a remote-controlled robot using 3D-printed parts and an Attiny85.
Step 1: Aquire Components
1x Atmel Attiny85
2x HXT900 from Hobbyking or any same sized micro servo
1x 3,7V LiPo battery (e.g. http://www.dx.com/de/p/tigers-3-7v-600mah-15c-lith...)
1x HC-SR04 Ultrasonic range sensor
1x 38kHz Infrared receiver (e.g. https://www.conrad.de/de/ir-empfaenger-sonderform-...)
1x 9 x 4mm switch (or use a jumper)
3D printed parts: http://www.thingiverse.com/thing:965449
Print the top and bottom parts with the flat side down and supports enabled.
Depending on your printer and servos you will have to sand those parts down a bit.
Step 2: Electronics
Modify the servos for continuous rotation. You can find a nice tutorial here:
Connect the components as shown in the circuit diagram.
It may help to use a small prototyping pcb and thin wires.
Step 3: Programming
You can program the Attiny85 using Arduino code and an Arduino as a programmer:
The full source code can be downloaded from this Instructable (or the Thingiverse page).
The infrared receiver works best with Sony remotes.
You will have to flash the code to an Arduino and output the data via Serial.print().
This way you can find out which button corresponds to which code.
Step 4: Assembly
Place the components inside the robot using hot glue.
The two halves of the 3D-printed shell can be assembled using the screws that come with the servos.