I have a brush from Rubberset that is almost exactly the same that i'm working on right now. As i was cleaning it up i realized that the top and bottom unscrewed from each other, which i thought was pretty cool!
Was this the case for your brush also?
The top and bottom are threaded, but I have no photos showing the threads. I'll see what I can do.
Use caution when checking for threaded handles. I had one of the bases crack when applying too much pressure. I will be using the top of the handle with a wood base to replace the broken piece.