In the creation of the finger, what planning is needed

 In the creation of the finger all knowledge (of the world) needs to be known in order to fashion it.

From its (the fingers) interactions, balance with the brain, ability in conjunction with the body it's nimbleness, sensitivity and fluidity. The finger was built with all body parts in mind. 

It's harmony and balance with the rest of the body, it's functions that are exhaustive ranging from hard to ease, its ability to heal the body, to cook, build, create,  clean, play and communicate. 

It's limitedness (length, number and width), it's nimbleness to strike a fire, sensitiveness,  when interacting all aspects of the creation. Neither too hard, too coarse, or too frigid perfect for the all that's around, no surprises it cannot handle. To interact with the unique world perfectly. 

In the creation of the finger only the ONE WHO IS THE MOST KNOWEDGEABLE (Al-Aleem) and Powerful (Al-Azeez) Can produce it.  

The prophets and messengers came with a choice with arguments to reflect upon the signs and to accept and reject. Arguments could be countered but the choice was there. The Law given had in itself a way to  goodness, worship and inclined the soul to it, the Argument there is one God, alone and he deserved to be worshipped is in itself a powerful argument appealing to the Fitrah (The innate nature) of the self wanting to worship and thank God. All this could be rejected with arguments both old and new. Miracles used at times to strengthen the argument. With the advent of science the "Signs" can be seen in detail, the Cell, the ratio between chemicals and all aspects of the creation. But the "principle" holds true, to accept and reject the signs.