I recall seeing a full-sized mockup of the James Webb at the South by Southwest about ten years ago. It was accompanied by a small traveling exhibit about the mission and some folks from a NASA (or Northrup?) education team to answer questions. They had been taking it to cities and museums across the country.

Not sure where it is now or if there are multiple full-sized mockups, but I wouldn't be surprised if one ends up in the public collection at Udvar-Hazy Smithsonian Annex where many big NASA toys end up.

I don't know where it is currently, but according to this 2008 article it was on a world tour at that time.

https://phys.org/news/2008-07-james-webb-space-telescope-ful...