Bill and Ben/Behind the Scenes

Gauge 1 models
Bill and Ben’s model were custom built to run on gauge 1 track for the second series. The models were built from Perspex. They were painted using glossy car body paint and lined with red prostripe automotive tape. The letters on their saddle tanks were custom printed stickers.

In the second series Bill and Ben’s nameplates were made to be removable, which was required for the episode, The Diseasel, which centred around the twins playing a trick on BoCo to confuse him with their identical looks. Since the third series their nameplates were replaced with custom printed stickers.

Bill and Ben’s wheels were sourced from modified Märklin gauge 1 BR 80. The bufferbeam details were sourced from Märklin as well.

A behind the scenes picture of Bill's model during the second series reveals that the twins were to have numbers on their smokeboxes above their faces, as they did in the Railway Series. However, they were removed once filming began.

During the production of the sixth series Bill and Ben’s models were repainted in matte paint. In the episode, Buffer Bother, Ben’s buffers were temporally painted gold.

Eleven different facial expressions were worn by Bill and Ben on screen. The faces were first sculpted in clay and from that resin casts were made using a silicone mould. Some of Bill and Ben’s faces were duplicated in case they needed to wear the same facial expression in the same shot.

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.

Bill and Ben’s models were twice the size of their basis' in order to accommodate their eye mechanisms and motor. This was carried over to their CGI models.

CGI models
In 2009, the series introduced Computer-Generated Imagery (CGI) as a replacement for the show's long-standing live-action models. In 2013, Bill and Ben were created in CGI by Arc Productions. The model was "hand-sculpted" in Maya, a 3D animation and modelling software.

Bill and Ben have had modifications throughout the CGI series. These include:
 * Series 17:
 * Their faces became smaller, and were raised slightly higher up.
 * Permanent lamps and taillamps.
 * An additional sandbox was added on the footplate to mount the lamp.
 * An extra wood panel was added to the rear window to accommodate the taillamp.
 * Taller cabs.
 * Brass nameplates.
 * Red lining behind the "SCC" lettering on their boilers.
 * Red wheels.
 * External brake shoes.
 * Black domes and crossheads.
 * Brake pipes.
 * Yellow wheel lubricators on both sides, that connected to their valve gears.
 * Yellow siderod guards.
 * Series 19:
 * Their crossheads became grey again.
 * The text on their nameplates became gold.
 * Series 21:
 * Their crossheads became black again.

Voice Actors
Bill:
 * Jonathan Broadbent
 * TBA
 * Rasmus Hardiker
 * Tomoko Naka
 * Noriko Shitaya
 * Sakura Yoshioka
 * Sascha Draeger
 * Marek Bocianiak
 * Christian Greger Strøm
 * Scott Maurstad
 * Reinder van der Naalt
 * Alan Bravo
 * Dor Srugo
 * Yehonatan Magon
 * Silas Borges
 * Salvador Serrano Jr.
 * Antti L. J. Pääkkönen
 * Anton Savenkov
 * Loukas Frangoulis

Ben:
 * Jonathan Broadbent
 * Matt Wilkinson
 * Miyuki Hara
 * Hiromi Nishida
 * Noriko Shitaya
 * Sakura Yoshioka
 * Sascha Draeger
 * Wojciech Chorąży
 * Anders Sundstedt
 * Scott Maurstad
 * Reinder van der Naalt
 * Carlos Domínguez
 * Miguel Ángel Leal
 * Yehonatan Magon
 * Silas Borges
 * Miguel Ángel Poison
 * Joonathan Kettunen
 * Anton Savenkov
 * Loukas Frangoulis