The Great Western Brick Show will take over the whole of STEAM Museum of the Great Western Railway on October 10 and 11, with more than 100 LEGO models on display alongside hands-on building activities and a retail section selling sets, rare collectibles and a limited edition kit made exclusively for the event.

The show, now in its tenth year of Robot Battles and run by museum operator STEAM in partnership with Brickish, the UK community of Adult Fans of LEGO, began life in 2002 as a single collaborative train layout. It has since grown into the organisation's flagship event, with railway scenes, cityscapes, castles and vehicles built by some of the country's leading LEGO creators and several international guests. Councillor Matt Vallender, the council's cabinet member for culture, planning and regeneration, is understood to be delighted the museum will once again be filled with creativity, families and the quiet dread of standing on a stray brick in socks.

The headline attraction is the Great Ball Contraption, a 36 metre collaborative machine that organisers say is now the longest of its kind built in the UK, edging out whichever previous machine was holding the title in a shed somewhere nobody has verified. It is understood that STEAM, a building normally used to measure things in locomotives and tenders, has had to invent an entirely new unit for the occasion.

Museum staff are said to be quietly proud but also slightly anxious about what happens if a rival brick show in, say, Yorkshire, decides to build one 37 metres long, triggering an arms race that nobody in Swindon asked for and everybody in Swindon will now have to live with.

"We've had a train museum here since before you could buy a brick with a smile on it," said Brenda Pask, 72, of Old Town, who has lived there since before it was old. "Now they tell me it's going to be full of little plastic men instead of proper engines. Ron always said the real Great Western Railway took forty years to build. This lot's doing one longer than our garden path in a weekend. Makes you wonder what we were all playing at."

Gary Tench, Area Manager at Tench Paper Solutions in Westlea, said the contraption had given him ideas for the warehouse. "Modular, interlocking, scalable, that's basically our whole shelving strategy," he said. "I've floated a 36 metre toner run to head office, purely as a team-building exercise, Julie's already measuring the corridor." He added that he intended to attend "for research", bringing with him a demo of a song he had written called Brick By Brick, which he described as "not literally about LEGO, more a metaphor for Q3".

Advance tickets, including full museum entry, are available through the STEAM website, with organisers encouraging early booking given the show's popularity and the finite amount of floor space not currently occupied by a 36 metre ball run.

The Great Ball Contraption itself declined to comment, on account of being built entirely out of plastic and other people's ambition.