try to carve a swan and at least you’ll get a duck—aim reasonably high and you won’t fall far short
刻鹄类鹜kè hú lèi wù
鹄：天鹅；类：象、似；鹜：鸭子。刻个天鹅不象，不过还象个鸭子。比喻仿效虽不算成功，但还相似。fail to achieve what one set out to do, aim reasonably high and you won’t fall far short