@dlmiles: Yes, open_pdks is not very efficient on disk space. It first builds everything into a local directory. "make install" pares down the size considerably by checking if files are the same between PDK variants and making symbolic links where possible. I just got a large terabyte disk so I could stop worrying about it, but then I am the developer, so I compile and install multiple times per week. Otherwise, if you're not updating it regularly, I suggest doing the "make install" followed by "make veryclean" and "make distclean" to get rid of the locally build version and the source files, leaving you with about 10GB usage. The profligate use of disk space is a constant annoyance to me.