Small Self Storage on 50x100 lot

[Lesley Resnick]

Has anyone built a Small Self Storage.  I have a piece of land and It is 50x100 and zoned commercial.  I am considering building a small self storage.  Probably in the range of 2500-3000 sq ft.  I am not sure of the size mix.  Seems like 10x20 is the most popular.  I may build a mix since my optimization is an L shape building.

Is block better than metal?  There are a number of metal pre-fab companies out there.  If I do block, I would use my concrete guy.