Not having a handy supply of buss bar material I decided to improvise and used (I shudder to admit it... LoL) 3/4" copper water pipe, sawed down to an appropriate width to fit the breaker attachments - each buss bar is likely 3/4" wide, and since it hasn't been hammered flat or otherwise bent it remains in its original ductile state. Areas not in contact with the breaker tabs are insulated with heat shrink tubing.
The array of breakers is set up to provide 4 rows of breakers. The main battery connection is virtually in the center of this array. Each row of breakers is tied together with its own copper buss bar and that buss bar is fed from the central feed point with a large-gauge wire (I have less alternator output than most RV's so my feed wires are 10AWG).
I wondered how well this setup would work so I tested it using battery power as my source of energy and then applying a large resistive load to the circuit supplied by the breaker the located furthest from the central feed point. That particular breaker is a 5 amp breaker and at full rated load and a battery voltage of about 12.2VDC I had difficulty measuring any voltage drop between feed point and the breaker. This made me feel my solution was workable.
Never too content with going on trust, I've been re-torquing the circuit breaker screws at each annual inspection, and at the same time looking for any signs of heat distortion, arcing, etc. So far, 2.5 years after initial installation, all is well. None of the CB screws have experienced a drift in screw torque and other than some slight discolouration where my fingers touched the bare copper, the buss bars look the same as the day they were installed.
Net cost for these home-brew buss bars was about two bucks...