I'm working on a project where I have a rectangle that is set to a carve region depth of .4. Inside of that I need to create a ring that comes up .25 from the floor. I tried creating two circles (one inside the other) and setting the inner one to a carve region of .4 to match the rectangle and the other one to a carve region depth of .25 thus hopefully creating the ring I need. This did not work. I also tried additive and subtractive with no luck. Could someone please tell me how I can make this work?

Thanks!!!