haven't done it but if so i'd put put masking tape on all lines and score in the pattern. with the masking tape still in location, i'd smear in a tiny amt of clear epoxy (not water based but test out - ordinary glue may be ok) and then rip up one side to be stained after glue nearly set.

then stain the one side, and then seal all over it with thin lyr epoxy. rip up the remaining masking side when semi-set.
after set, roughly stain the other side. any mistakes just clean up over the now sealed first stained area.(that's w/ the can flag w/ only 2 colours)

test it tho i bet it'd work.

and if you totally screw up, as it's a ply s&g, just rip up the veneer and use diff veneers for the pattern, or same veneer but prestained before making pattern. like cut in a big rectang for the backgnd add a maple leaf on top.