http://www.zerohedge.com/news/2017-08-31/dhs-selects-4-contractors-build-prototypes-trumps-border-wall
I think this is my favorite:
DESIGN Penna Group’s proposal is for a double wire mesh fence that has a sheet of plexiglass lined with a one-way mirror allowing border patrol agents to see the Mexico side, but not the reverse. The fence would be 30 feet tall with a 6-foot footing, and both would be designed to sustain tampering by pickaxes, hammers, hand-tools, and torches for over an hour and a half. The double-lined, double-wire mesh design is often used in maximum-security prisons.