'Arry and Bert/Behind the Scenes

Gauge 1 Model
'Arry and Bert were built to approximately 1/32 scale and designed to run on gauge 1 track for the fifth series. The models were built out of perspex.

Different facial expressions were sculpted for 'Arry and Bert. The faces were first sculpted in clay, and from that resin casts were made using a silicone mold, some of Thomas' face masks were used as a reference.

The chassis had two motors, both powered by electricity from the track via the pickups on the metal wheels. The main motor powered the wheels, while the second motor (located at the back) powered an inside piston for the smoke mechanism.

The eye mechanism had two servos, one for up and down movement and one for left and right movement. The up/down servo was attached to the body. The left/right servo had a rod attached to the arm, which connected to a bracket. The eye balls were coupled to the bracket, and locked in by the face-plate, so whenever the servos were powered, the eye balls would move however the crew member desired.

Cgi Model
In 2009, the series introduced Computer-Generated Imagery (CGI) as a replacement for the show's long-standing live-action models. a year later, Arry and Bert were recreated from scratch in CGI by Nitrogen stduios. Their model was "hand-sculpted" in Maya, a 3D animation and modelling software. Photographs of 'Arry and Bert's Gauge 1 model were used for referencing. According to Greg Tiernan, every detail of the original television series models for each character is carefully reproduced in the CGI model. The models are subjected to many rounds of review before they are submitted to HiT Entertainment for final input and approval.