That would be my usual choice, phosphor-bronze wipers soldered onto a piece of copperclad. I have an ancient piece (bought goodness knows when) that is about 5 thou thick. I always bung a self tapper through the copper clad, in addition to some contact adhesive, just to make sure it stays put. Also, never bother with wipers for the centre wheelset, as these typically carry no load and will often be braked by wipers. I always polish the the wiping face of the phosphor bronze with a little brasso before installation; because Mr Henry (schoolmaster of my youth) who first showed me this technique always did so.
A simple alternative is to form and solder up two loops about 25mm apart in a length of 0.5mm dia nickel silver wire. Two self tappers through the loops to secure to the vehicle, arrange the free ends beyond the loops against the wheel backs.
A simple alternative is to form and solder up two loops about 25mm apart in a length of 0.5mm dia nickel silver wire. Two self tappers through the loops to secure to the vehicle, arrange the free ends beyond the loops against the wheel backs.