I wanted a true random number generator for GNU/Linux, so I built one from a DVB-T, rtl-sdr, rtl-entropy and some systemd scripts rtl_random.service and rtl_rngd.service. I put the receiver in a tin can and sealed it with aluminum foil to prevent my evil neighbors from interfering with my random numbers. Now I can see the random numbers flowing in from /dev/random. Below are some pictures.

Elephant RNG parts
Elephant RNG parts
Elephant RNG
Elephant RNG