Semroc Mini Optima Build, Part 4, Interior Tube and Fin Shaping

The top of the engine mount is glued into the insulator tube.
The upper white centering ring is recessed 1/16" inside the tube.

There are six fins on the rocket, on the left is the upper fin.
The lower fin has a fin tab that glues through the pre-cut fin slots and onto the engine mount tube.

The leading, outside and trailing edges of the fins are rounded.

Be careful when rounding the upper, smaller fins. The grain runs parallel to the small leading edge.