Estes BOSS Kit #7316, Build, Part 6, Engine Pod Reinforcement

The yellow rings (Part M) are glued in even with the back of the engine pod tube.

Here I'm using the flat surface of the sanding block to press the ends even.

I used a little bit of CWF applied with my knife blade to fill the seam inside the reinforcement ring and around the seam. 

After it was sanded to surface,

I applied some medium CA glue over the outside of the ring edge to seal the surface. Sanding followed. 

Here I'm sanding the CWF filled inside ring seam (Yes, I fill the inside seam if it can be seen on the finished model) before the CA glue was applied and sanded. Some 400 grit was wrapped around a dowel.