How do you implement an o ring for a polygon with n number of sides in inventor

I am designing a laser cavity and I need to implement an O -ring for the box that I am designing and I am stuck at this . I am an intermediate user in inventor. So the people willing to answer can please spend a few more minutes and tell it elaborately.

4 Answers

This is the outline of my design

I need the O ring on the top of the design exactly on the thickness between the two outer extrusions and can you tell me the issues what are in the design

I tried do that but I think it's not correct

OK that is a rubber type seal .Thanks for explaining me as I am an intermediate user so probably I did not get the question correct I think. I got what I want now. Thank zou for helping me out Jonathan.