Assembling the robot requires a bit of finishing of the 3d print. The original instructions by user outcastrc on thingiverse are
1. The chassis is designed to use standard size 360 degree rotation servos.
All holes are designed around 3mm screws, with most holes printed at
2.5mm so you screw directly into the plastic. 2 holes (25mm apart) are
included on the front of the chassis for mounting a sensor.
2. The battery plate includes everything you need to mount a 5 AA battery inside and an arduino uno on top. The plate also includes 2 holes on each side set 25mm apart to add sensor modules as needed. Smaller packs could be used with a piece of foam to act as a spacer. There is 20mm between the plates.
Wheels use any standard 1.9 RC tires and bolt to the round servo horns.
The castor is designed around a front tire from a micro RS4. It uses 4x8mm bearings for the wheel as well as the pivot. Black electrical tape could be used as well to create a tire for the wheel. I use 4mm stepped bushings in the bearings so I can use 3mm screws. An adaptor is included to add a sensor module to the back of the chassis if needed.
3. A stand is also included for storing / working on your programming. It keeps the tires slightly off the ground.
The complete instructions on assembling the robot are in the instructions section of this project.