the good patches are the round ones with a read glue kind of seal on the outside...
I have patched many a tube...all tubes are rubber! jajajaja
the important thing is to sand the affected area well and let the glue tack dry first...the press firm for 5 minutes or so under a rock..there is always a rock for this...and inflate the tube to 5psi and install in the tire
THEN install on the wheel
that way NO PINCH FLATS
3 spoons are better than 2, but if you have a crescent wrench or long screwdrivers you can compromise