B9 Robot Collar

B9 robot collar reference. See the full B9 robot construction overview.

Frequently Asked Questions

What is the B9 robot collar? The collar is the accordion-style flexible section connecting the B9 robot torso to the head assembly. It is one of the most visually distinctive elements of the robot’s silhouette and is visible in almost every shot of the robot on the original Lost in Space series.

What materials are used to build a B9 collar replica? Common approaches include foam-based construction with medium-density upholstery foam (2.0–2.5 lb density) covered with black neoprene fabric or vinyl, vacuum-formed black ABS or PETG over a sculpted pleat profile, and cast silicone or flexible urethane rubber from a mold. The foam-covered approach is most common; cast rubber is most accurate but requires the most mold investment.

How many pleats does the B9 collar have? The exact pleat count varies between seasons — the collar was rebuilt or modified at various points during the three-season production run of Lost in Space. The Season 2 and Season 3 configurations are most commonly replicated, and the B9 Builders Club forums document approximate pleat count and proportions for each production year based on reference images.

What structural requirements does the B9 collar have? The collar must support the head assembly weight, allow head rotation without binding via a central rigid aluminum tube (3–4 inches diameter) that serves as the rotation bearing surface, and accommodate wiring for head-mounted electronics through a wire chase in the center of the tube. All three functions must be planned before finalizing the collar structure.