Trimming Nav Light Covers

I'm not the original builder of my '6 but am replacing 2 crazed and cracked nav light covers. I have the new items from Vans but need to trim. Using packing tape I pulled the lines from the old lens and wing junction and have that as a guide. Any tips on how to trim would be welcome.

I just did one for my 9. My only advice would be to take it slow and be careful. I am also not the builder of my airplane. It wasn?t as difficult as I first thought.

My very first injury while building came from this very event. Imagine using an exacto knife, some resistence, and pulling backhand toward your thigh... Eventually I used a pair of Cutco sissors, trimmed slightly over the line and sanded to fit.

You can cut these with tin snips easily, then sand to the final size.