This spell is crazy useful if you are dungeoning in a building with stone walls. 

Being chased by baddies? Block the hallway with stone.

About to be blown to kingdom come? Raise a stone wall for cover, or sink yourself into a pit.

If your DM lets you, shape some stone around the legs of an enemy, and prevent them from moving.

Mold Earth and Shape Water specify that they cannot be used directly against a creature.  

Shape Stone does not specify that it cannot be used offensively; thus we can infer that direct offensive actions are within the purview of the spell. 

Good hunting, Engelbert. 

I had a similar idea. Could you theoretically petrify someone with this spell? Especially interesting to creatures sleeping or laying on a floor made of stone.

You definitely could do what you're thinking in Concept. It won't give the Petrified Condition, however, so instead they'll just be in what is essentially a stone case that'd suffocate them (except for creatures who don't need to breath).

And before anyone thinks it: no, this (RAW and RAI) wouldn't work on a petrified creature as it's still a creature and even if you did it wouldn't work for very detailed things.

For rule of cool though, I'd probably allow it for small neat aesthetic things (or a strengthen 'mending' cantrip if either nobody has it or they simply can't use it for whatever reason)

Assuming you succeed on initial saving throws, could you use this spell to place a rock against the face of say, an umber hulk or basilisk, and cover their eyes, negating their gaze effects?

I don't know how practical it would be, but I think this could be a pretty assume use for the spell

God imagine what you could do with this to someone affected by Flesh to Stone

Does the final product have to be smaller than 5x5? Can a player uses 5x5 stone block to make a bridge 5 ft. wide x 0.5 ft thick x 50 ft long?

RAW the spell says you can shape a small passage through a 5ft thick wall. The extra stone would have to occupy a space outside of that initial 5x5x5, so it seems reasonable your creation could extend to an area beyond that.

It's also a touch spell with a casting time of 1 action. I think it would be fine to let someone shape a bridge under them as far as their move would allow.  Assuming the caster could use a bonus action to dash you could double that, and reduce the thickness accordingly.

That would give you a 5ft wide bridge 25-70 ft long and between 4-12 inches thick.

Does the final object need to be the same volume as the original stone? For example, could I shape a tiny pebble into a big 5x5x5 cube?

FYI my understanding is that the answer to this is that, yes, volume is indeed conserved.

Pair this with flesh to stone and auto kill boom! Shape there head off!

It says you can create stone weapons, but are there any official rules on how to handle weapons made out of stone? There has to be some sort of detriment that makes them less useful than forged weapons.

Ok so heres a question. 
A druid in my campaign has taken stone shape and wants to create a suit of half plate armour so he can wear this and gain the AC of metal armour as a druid. 

Would stone shape be able to create armour or is this a step to far? 

Make stone spheres, use catapult to launch them.

Can be used to carve a shelter out the side of a rock.   Or during break periods hollow out a rocky area to make a structure or base.

Quote from Rulebook >>

Ok so heres a question. 
A druid in my campaign has taken stone shape and wants to create a suit of half plate armour so he can wear this and gain the AC of metal armour as a druid. 

Would stone shape be able to create armour or is this a step to far? 

Not too far. I'd consider doing something like increasing the weight & stealth/acro penalties, as it's usually heavier (not folded) and the character is unlikely a smith.

Alternately homebrew some brittle rules like 1d4 on a hit, on a 1 it decreases AC by 1. Give the player the choice.

This spell is probably the best for creating stone figurines. You can create a stone version of yourself and then cast animate on it. And if you are a DM then you can use this spell to create a great trap.

Quote from Rulebook >>

Ok so heres a question. 
A druid in my campaign has taken stone shape and wants to create a suit of half plate armour so he can wear this and gain the AC of metal armour as a druid. 

Would stone shape be able to create armour or is this a step to far? 

Just my opinion, but that sounds like a step too far to me.  Plate armor has all sorts of straps and buckles to distribute the weight across the body, and the spell explicitly says it can't do moving parts more complicated that a coupld of hinges and a latch.

Even if you choose to allow it, a suit of armor shaped out of stone will be much thicker and probably heavier than a suit of plate mail, I'm thinking.  And it will less durable in the end.  I'd say anything that deals bludgeoning damage will break away bits of the stone on impact.  Maybe piercing too, your call.

Bottom line: making a functional, durable suit of armor requires more than just shaping any given material into the same form as the armor you're imitating.

this spell just makes me want to create a character that materialises daggers out of nothing. pairing this with spells like ice knife and shadow blade and make a bladesinger wizard. shame it would take two actions to create knives and throw them with this

Quote from Catskinner >>

Mold Earth and Shape Water specify that they cannot be used directly against a creature.  

Shape Stone does not specify that it cannot be used offensively; thus we can infer that direct offensive actions are within the purview of the spell. 

Good hunting, Engelbert. 

 l just looked at mold earth. here is a exact quote of what it says. note the lack of a "you cant use this to bury someone alive":

You choose a portion of dirt or stone that you can see within range and that fits within a 5-foot cube. You manipulate it in one of the following ways:

• If you target an area of loose earth, you can instantaneously excavate it, move it along the ground, and deposit it up to 5 feet away. This movement doesn’t have enough force to cause damage.

• You cause shapes, colors, or both to appear on the dirt or stone, spelling out words, creating images, or shaping patterns. The changes last for 1 hour.

• If the dirt or stone you target is on the ground, you cause it to become difficult terrain. Alternatively, you can cause the ground to become normal terrain if it is already difficult terrain. This change lasts for 1 hour.

If you cast this spell multiple times, you can have no more than two of its non-instantaneous effects active at a time, and you can dismiss such an effect as an action.

Does stone shape make noise? when making a pathway through a wall would npcs notice? Also is the volume conserved?