u/Icy-Tax-3612

I'm designing a J-class KNSB rocket motor and I'm wondering how on Earth the grain spacing is supposed to work. I have multiple sources telling me many different things such as gluing, using o-rings, or using rolled paper. Some of the papers even suggest to just cut a chamfer on the edges to get the faces burning. I just want some suggestions from people who have done this many times because I'm stumped on how I need to space these grains.

In OnShape the spacers are supposed to be rolled paper. Also if you notice anything off about the rocket motor design itself, please tell me.