This is an interesting thread so I thought I would bring it back up again.
My shop is 60' x 100' with the front half the heated shop and the rear half project and equipment storage. The 15' walls provides ample height for the lift that is still on the to do list. It was constructed in 1968 by my family using 2" and 3" drill stem pipe, oak and strong barn corrugated tin.
The welding tables are steel 55 gallon drums filled with sand and topped with 3/8" plate. The work bench is 20' long constructed of 2" oak cut at our neighbors saw mill back in the 1960's.
It is not fancy but is roomy, solid, warm and my favorite place to be.
Thanks for listening.