Hard boil eggs for 10 minutes. Transfer to ice bath. Peel once cool.
Make cucumber dill filling. Beat cream cheese smooth. Add dill, lemon juice, garlic powder, salt, and pepper.
Make smoked salmon filling. Beat cream cheese with lemon juice and zest until fluffy.
Make egg and chive filling. Mash eggs with fork. Add mayo, mustard, chives, salt, and pepper. Mix until slightly chunky.
Spread each filling generously on one slice of bread per sandwich.
Layer cucumber slices over cream cheese for cucumber sandwiches. Top with second bread slice.
Layer smoked salmon and dill over lemon cream cheese. Top with second bread slice.
Spread egg filling and close egg sandwiches. Press all sandwiches down firmly.
Cut off all crusts with a sharp serrated knife.
Cut each sandwich into fingers, squares, or triangles.
Wrap in cling wrap with a damp paper towel on top.
Refrigerate for at least 30 minutes.
Arrange on platter. Garnish with herbs, lemon slices, and edible flowers. Serve cold.