Two intersecting non-decal objects.
Default: Create floating Panel Decal
ALT: Topo Slice, follow target object's topology closely
SHIFT: Create smoothed Panel Decal
CTRL: Create subdivided and smoothed Panel Decal
If a sliced Panel Decal is selected, the Unwrap tool will appear in place of Slice in the Pie Menu.
Unwrap recreates the panel decal UVs and should always be run, after panel decal geometry has been changed manually.
Keep in mind
If you edit panel decals, make sure you keep them all-quad polygon strips.
Default: Unwrap all-quad Panel Decal
Alt: Unwrap + shrinkwrap all-quad Panel Decal