RE: Slanted Risers, which Cathe workouts are you using ...
Carolyn,
If you aren't planning on using the risers to form a ramp-type apparatus for cardio, then I think you would be fine with only one riser. I am currently only using them to make a more stable incline/decline bench, and all I really need is one.
Wish I would have thought of your idea!
HTH.