Scale of what? The Mazda 13B? How about a scale Le Mans winning 1994 26B four rotor. That would be cool.
The only plans I know of are for the SW92 from www.vth.de. I have them, the engine is 9.2cc, and was designed by Julian Faleki of Poland in the early sixties. It is all on a single A1 sized page.
Interesting plans, I haven't built it but it appears to be about as far as you can simplify the design. The Trochoid is simplified to an oval, with increased apex seal stoke compared to normal Wankels. Obviously hobby CNC was still a fair way in the future then, and the designer probably correctly figured that few would build it of you first had to build a trochoid grinder.
It is entirely of steel, with the wear surfaces to be chromed. It has no side seals or e-shaft seals, so compression is controlled by rotor clearance, as with the OS-Graubner. I bet it is a really messy engine in service, as the blow-by runs straight out through the E shaft bearings. These are standard metric bearings, so I supposed you could use seal bearings.
The rotor bearing is a roller bearing where you make the rollers which run between rotor and E-shaft.