My reflective step wedge target is found in an old Kodak darkroom data guide.
It is also posible to work from instructions in the 'Way Beyond Monochome' book of Ralph Lambrecht and make your own target on photo paper.
Basically you work systematically increasing expoisures on a sheet of paper under the enlarger with no neg in the carrier with one inch strips progressively being uncovered between exposure intervals.
The page of instructions is somewhere at home.
If you are really serious about honing your craft, Ralphs book is an extremely useful reference that you can read many times and still learn and get ideas from.