I know a lot of people could be confused at the intent in the title so I'll try to make this as clear as I can from the start. I am NOT considering converting a cello into a small upright bass. That's been done. I don't want to go smaller, I want to go BIGGER. I used "5/4" as a kind of indication of this size as a kind of extrapolation above 4/4, 3/4, and 1/2 cellos. Why? Because I'm a big guy and I might want to play cello. How big am I? I'm in the 99.6 percentile in height. That means if I was in a room with 999 other Americans then I'd be taller than three, maybe four, of them. Another answer is that after seeing attempts about cello to bass conversions I thought it might be fun to at least see what it would take to spin that around and see if and how "super-sizing" one could be done. For this discussion, at least to start, I'll discuss four variations. A cello conversion based on a "full size" bass or "reduced size" bass, and with each a "bass like" EADG tuning and with a "cello like" CGDA tuning. I'll define "full size" as something that's 4/4, 3/4, or 7/8 scale, meaning a 44 to 41 inch scale length. I'll define "reduced size" as a scale length of 34 to 39 scale length, which means a scaled size of 1/2, 1/4, or 1/8. I'm stopping at that low end of scale length because these lengths of strings should be pretty common for the most part, and if we go much further in going short then it's just starting to look like a cello. If I'm not mistaken the open G string on both the cello and bass will sound the same note when plucked. If I find a "standard" five string set, with EADGC strings, then I'm off to a start for an oversize cello set of strings by setting aside the E and A strings. The D string will be in first and tuned down to C. The G string is put in and tuned to G, of course. The C string would be tuned up to D. What of the fourth (A) string? I don't know. If we want this same "full size" bass to sound like a cello, and be tuned EADG like a bass, then this might be much the same as the first. Get an EADGC five string set, set aside the E and A strings, install, and then tune. What of the fourth (G) string? I don't know. With a 1/2 or 1/4 size, and CGDA tuning, then maybe we can more easily find strings. We could use "full size" strings and cut them down. That could mean still using an EADGC five string set but setting aside only the one E string. Cut down the A string to fit the shorter scale and tune to C. Same goes for the G, D, and A strings, just being cut down from the A, D, G, and C. Can this be done? Finding strings for a shorter scale length of 34 inches (like on upright basses that use bass guitar strings) might be easier than a longer 39 inch scale (as on a common 1/2 bass). A "reduced size" bass taken an octave higher, into the cello frequency range, should be doable. Again starting with a "standard" five string set, set aside the E string, cut them down, install, and tune. If I'm mistaken and this kind of conversion has been done before, and I suspect it has, then I would appreciate bringing that to my attention. Would I actually try to do this? I don't know. I might just for grins. It's an excuse to buy another bass, even if I don't leave it tuned as a cello. Again, if I want something that sounds like a cello then why not just get a cello? Did I mention my height? Also, if I tune it EADG and I have a same size bass (as a bass) then I'm playing a cello (-like instrument) and not having to learn new finger positions or anything, I'd just play.