Monokote Trimming Tool
 

Passing along a technique I learned from a master modeler: pulling-to-shear excess material against a blade which avoids cutting underlying structure or covering -

Added a twist by use of 3 single-edged razor blades butted together end-to-end to create a longer tool to do the same job a little quicker.

Works very nicely.
How about when you put on the second color and want a straight trim line on top of the MonoKote which is already in place, like where the covering on a compound curve turtle decks meets a fuselage side?

Using just one sharp single edge blade, I'm using the same technique to trim the overlapping piece of Monokote - e.g. on a wingtip - a difficult area that some modelers avoid using different colors on and also with compound curves. There is a learning curve and it takes longer, the tighter the radius you're following because of the small contact area with the blade. A flexible plastic straight-edge comes in handy here to place a Sharpie line down to follow; a paper towel dampened with alcohol can be used to wipe the Sharpie line away after the trimming process is complete and edge sealed down. I have also used the edge of masking tape to follow in place of a Sharpie line. If I encounter a stubborn place where the material won't start shearing, I'll slide the blade back and forth while pulling on the excess to start the shearing process again. I go through about 5 single-edge blades per model.

Note that the covering must be stretched past the trim line and the excess material must not be stuck down anywhere beyond the trim perimeter when trimming the excess off.

Alternative method to scribe a trim line:

On a smooth flat surface, level and immobilize the fuselage (or any part for that matter) for initial or overlapping covering. A simple surface gauge with which to clamp a Sharpie at the desired height (like the union between the fuse sides and turtle deck) allows a line to be drawn around the entire part that will be as straight as your work surface is flat. Once this is done, you have a line to follow using this same trimming technique.



https://cimg9.ibsrv.net/gimg/www.rcu...6f7f54ad60.jpg
Simple surface gauge - used to mark a tube to length in this case - but is what would be used to mark any kind of part for a trim separation line after leveling the part -

Once I used the monokote covering to cover a hole in the wing of an air plane
. It irons on....comes in lots of colors to match.