I'm modelling a curved dovetail for CNC routing. (See attached file) Have modelled the short side OK. Can use the cavity feature to create the complementary feature in the long side of the box but can't figure out how to introduce a clearance (0.1mm, in this case) so it will fit together.

Think I can do it with a lengthy workaround involving converting entities from the original sketch, then off-setting and fiddling until I have some closed sketches to use for an extruded cut but this seems cumbersome and like an opportunity for me to learn a better way.

Thanks for your expert advice,

Andrew