You mean mechanically configurable, or configurable via software?
Most Logitech mice are very configurable via software, if you want to change button assignments, cursor speed, cursor acceleration, etc. Most also have weights inside the mice that you can remove if you prefer a lighter mouse.
That's not old man, I still have my R.A.T. 1, although the left click has recently become intermittent. Trying to figure out how to get it open without breaking to put in some kaihli GM 4.0 buttons to give it some new life, although it's terrible for gaming (they put some input filtering on the sensor to help keep it in a straight line, even if that isn't your actual intention). Anyways, the other option would be to try to modify or even 3d print your own mouse/parts. I'm sure someone's done it before you could use as a pattern at least.I feel you. Ocz had a big mouse but that is no more. I have an old rat 7 that still works fine though. It has to be at least 5 yes old now.