The Snap-on Tools toolmaking factory in Elizabethton is preparing for a major expansion of the facility and will present the preliminary site plans to the Elizabethton Regional Planning Commission for preliminary approval Thursday night.The site plan is for a 25,350-square-foot addition to the factory at 2195 State Line Road. J.A. Street and Associates of Blountville will be the general contractor on the construction project.The parking lot will contain 140 new spaces, resulting in a net gain of 59 new spaces.