I wrote:

"It would certainly be easier if the intervals between adjacent strings were all fourths (ascending), but it's impossible, if the top string is to be two octaves above the bottom string. This would require twelve strings and probably not be very conducive to playing:"

Sorry, this is an error! In this case, the high E would be 5 octaves higher than the low E! Watch out for snapping first strings! (Or very, very low low E strings.)