I don't think any famous builders are or were involved with rondo. I could be wrong. headstocks used to be straight up Fender copies. Then they were this weird paddle shape (many are still there). Now they're Sadowskyish.
I also don't think there were any famous builders involved. I've not seen any Fender Copies, but there certainly could have been. I only became aware of Rondo around 2001 or so. Some details are fuzzy, but here's what I remember.
Back in the early 00's most Rondo basses had the shape that was somewhere between Lakland and Fender. I had two of them and rather liked the shape. There was also an enlarged Fender'ish shape with a fishook undercurve. I think these co-existed with the Lak'ish headstock for a while. I've heard that some sort of legal issues forced the retirement of the Lak/Fend, but I don't know for sure. I had a Fishook 5'er around 2003 or so like this.
The Fishooks were the only version for a while and IIRC, this was not genrally well recieved but they lasted until the paddle shaped headstocks came out some years ago and at the same time Rondo Gave most of their SX basses model designation "Ursa".
A few years ago they began putting a Sadowsky'ish headstock on their better-brand "Andromeda" J-basses which were J-basses with slightly upgraded features in the $250 range and only available occasionally.
Around the same time as the Andromeda's the orginal Lak/Fend headstock (or one very similar) began to show up on their 3/4 scale "Rose" basses ( starters in "girl" color schemes) and more recently something similar has appeard on their sub-SX "Omega" brand which has no markings on the headstock.
Now the Sadowsky'ish headstock has started showing up on quite a few of their "Ursa" basses. I think I've heard that they're all going over to this shape, but don't quote me on this.
My favorite headstock is still the early Lak/Fend shape, which I think may still be available on TEAM international (the company that builds SX's) instruments under different brands which are sold in other countries. (Rondo is the sole TEAM distributor in the USA) Regardless, I find the new Sadowsky'ish design to be a HUGE improvement over the Ursa Paddle or the fishook.
