Model with #laserscanning data in Solidworks. Export data as ASC file from Realworks to use ScanTo3D plugin or as an e57 if you are using xtract3d. Allowing you to use full as-built measurements of a site and design new fabrication which will fit exactly.
ScanTo3D plugin.
https://www.youtube.com/watch?v=sBdxKTGzdJc&list=PL1TStJR6oVYdLuWf4few4pII-PGe-kkzn&index=4
XTract3d
https://www.youtube.com/watch?v=rV1giWmNAqE