There's a great sequence telling how they'd go down to the local Woolworths to scoop up dozens of Airfix kits to use as parts for detailing vehicle models and sets...along with "plastic boxes, beach balls, and salt and pepper sets" that they could turn into exotic-looking bits of machinery or backgrounds. But my favorite quote on that bit comes from model-maker Mike Trim:
"It didn't always work. Sometimes we got it wrong. There is one thing that haunts me...and that's a lemon squeezer stuck on the wall at the back of Thunderbird One's set."
And in the next shot they show Thunderbird One's launch bay with -- clear as day -- the kind of dish-type lemon juicer any of our moms might have had in the kitchen drawer, stuck prominently on the hangar wall...backlit, to give a suitably futuristic eerie glow.
The sheer inventiveness of 'primitive' early-'60s technology is really pretty amazing. The puppets' mouth movements were actually lip-synched with a novel electronic system cued by the voices on the audio track...which had to be carefully calibrated to account for different pitches and tones of the various actors' voices.
All the pyrotechnic and water sequences were shot at double film speed, then slowed down for an incredible degree of 'realism' for editing. They actually recreate one of these sequences -- a refinery explosion -- showing what looks like crappy fireworks going off in real time...but which shows as majestic multiple detonations that would nearly do modern films proud, when 'half-cranked' to slow everything down.