Estes Space Shuttle Columbia Build #1385, Part 19, Setting The Gray Trim

This Gray trim on the leading edge of the wing underside didn't work! 

I'll still show the process. Sprayed decals can be a good workaround, especially a simple color band wrapped around a body tube. The more complex the surface, the more likely this trim may not be an option. 

The paper template was cut out. A glue stick was used to stick the paper down onto the gray painted (white) decal sheet.

The decal sheet was cut out with scissors around the paper template.

The paper template was peeled off the decal.

There was some paper fibers and glue still on the gray painted decal.

Not a concern - this will dissolve when the decal is soaked.

The gray decal trim was soaked and set over the leading edge of the wing.

Here the wing is held up to a bright light to see the overhang and visual placement of the decal.

After the decal thoroughly dried - 

With a sharp blade the decal overhang was trimmed off.

Go slow, don't cut into the leading edge paint or balsa.