New Way Nike Ajax Build, Part 9, Tunnels Shaping

I thought the balsa tunnels would be too weak when trying to sand the trapezoidal shape into the sides. (See last picture below.)

I cut them out of 1/16" thick basswood using a kit supplied balsa piece for a template.

Here's four of the upper body pieces below the original kit piece.

GOTCHA: Well, got me anyway! I cut the lower, longer tunnels were fine cut from basswood. They fit a straight  tube surface well. 

On the upper, shorter pieces, the kit supplied balsa is more flexible. The balsa strip is easily pressed into the adapter dip and over the nose cone shoulder curves. I ended up having to cut notches in the upper basswood strips and "cracking" the wood slightly to fit the angle changes. More on this later.

If you want an easier build, stay with the balsa strips supplied with the kit. But, the balsa grain is more difficult to fill.

The strips are sanded to a trapezoid shape, shown below.

I marked the tunnel sides with a soft pencil. This gives me a better contrast, I can see what is sanded off.

Use a sanding block to keep the side corners sharp.

Looking from the back end, here's what you should end up with - 

The basswood is stronger and will hold up to more aggressive sanding.