Designed for 3D printing. Just orient each model in a reasonable way (e.g. chassis gets printed upside down). No supports needed.
Print order and quantities:
[1x] YellowBot_02 - chassis.stl
[1x] YellowBot_02 - controls.stl
[1x] YellowBot_02 - mech mount.stl
[1x] YellowBot_02 - arm.stl
[2x] YellowBot_02 - intake_wheel.stl
[4x] YellowBot_02 - side bumper.stl (two red, two blue)
Motors are the common yellow toy motors available online, like these.
Motors attach with small zip ties.
All fasteners are standard M3 screws (lengths of 5mm and 8mm) and nuts. A kit like this should do it.
Arm servo is an MG 996R (common import servo), like this one.
Intake motors on the arm are N20 300rpm 6V gearmotors like these. Wheels press on and are locked with M3 set screws like these.
The "spatula" at the bottom of the intake is some ~1mm thick acrylic cut on a bandsaw (but any rigid flat stuff cut with any method would work).
For MiniFRC, it was required to have some form of team identification (team number and red/blue team designation). I did this with the "side bumpers". Four were printed: two red and two blue, with team number written on.
Lastly, the "YellowBot_02" text on the back bumper can be made visible by painting with a thick paint pen. (The robot shown has the text inset, but the model uploaded has it extruded out a little -- the latter should be easier to paint.)
The control electronics are an ESP32 dev board riding atop an Alfredo NoU, a beta version of a robot controller from Alfredo Electronics (no link available yet). The controls module is modular, so you could redesign it to use a more traditional Arduino+motor shield just by tweaking the dimensions and hole positions.
Power source can either by a 6xAA battery pack or a 9V Li-ion pack. A regular 9V battery should not be used -- they can't source enough current and die fast.
Connections are pretty straightforward. Battery into VIN, drive train motors into M1 and M2, intake motors into M3, servo into the first servo port (D16). Cinch well with zipties. Coil the intake wires so they flex without tangling.
Software is based on Arduino and is included in the upload (see .ino file). Requires ESP32 with Alfredo NoU, including the NoU standard library.
Uses the MiniFRC Drivestation via bluetooth to a laptop.
Want to build this?
If you want to build this bot but don't have access to an Alfredo NoU board, you can substitute an Arduino Uno with bluetooth module and motor shield. Parts list can be found in this doc, directions here, software here.