Cameron Balloons, the firm behind millionaire adventurer Steve Fossett's five balloon record attempts, took two days to make the giant legwear.
The remains of the 40-foot Willow Man in Somerset are being used to launch Wrong Trousers Day, in aid of children's hospitals.
They were made by a balloon manufacturer for the giant figure, which was attacked by arsonists in May.
Fundraisers across the country are expected to don "outrageous" trousers for the charity day on Friday, inspired by the Wallace and Gromit film.
Cameron Balloons, the firm behind millionaire adventurer Steve Fossett's five balloon record attempts, took two days to make the giant legwear.
They used enough fabric to make 85 pairs of normal trousers.
The Willow Man was dressed - in the Fraser tartan - with the aid of a 30ft cherry-picker.
The sculpture was built in a field alongside the M5 near Bridgwater by Serena de la Hey.
Nick Capaldi, chief executive at South West Arts, said: "We were very sad when the Willow Man was destroyed.
300,000 trousers
"The skeleton remains and we're delighted that Serena de la Hey has agreed that it can be used for such a good cause."
More than 300,000 people are expected to dress up for the charity day.
They will be raising money for children's hospitals and hospices in Bristol, Cardiff, Leicester, Manchester, Newcastle, Nottingham, Sheffield and Stockton-on-Tees.