Semroc Laser X, KV-33 Build, Part 11, Red Paint & Spikes

Here's the mask for the larger red fins - 

Marked Scotch tape went into the root edges,

Brown masking tape filled the areas between the fins,

A plastic grocery bag was taped over the top.

After the tape mask was pulled - 

The outside edges of the fins were sanded down to the bare balsa.

The spike sides are a rounded surface, some of the exposed bare balsa might show through on the sides.

TIP: This was one of the rare instances where I could use a Sharpie for touchup that wasn't black ink. The red Sharpie was a good match - that doesn't usually happen with other colors.

Just the edges of the bare balsa got some red.

The black spikes were also scraped for gluing.

Set the spike beside the outside edge of the fin. I used a small wrap of masking tape to make a border edge.

The gluing line was scraped using my knife, ending just inside the tape borders.

Here's the spike glued on.

Again - Use white glue for this visible glue fillet. It dries clear.

Note the spikes aren't centered on the outside edge of the fin.