How low can you go?

I can find out very little about this Lobro Bass Spring that I found on a Google search for something else entirely. It seems to be some kind of bass diddley bow with a screen door spring acting as a string and is tuned to A1, i.e. the low A on a piano. It appears to be the work of a fan of the German industrial/noise band Einstürzende Neubauten. It's not strictly speaking a guitar, but it's a relation of sorts.