Let's say I am a sorcerer with extended spell metamagic available, and I choose to cast a delayed blast fireball with 10 sorcery points, which yields a 17h fireball (and more than 10000d6 damage on failed save if left for full duration). I cast it on a flask and close it, so it would not count as being touched. A couple of questions:

1. Can I carry it?


2. Can I throw it?

You can't carry it around or throw it in a glass jar

The bead stays in one place for its entire duration

Delayed blast fireball says:

A beam of yellow light flashes from your pointing finger, then condenses to linger at a chosen point within range as a glowing bead for the duration.

The spell tells us that the bead will stay at the given point for the entire duration at the spell. It does not outline any way the bead can be moved except by throwing it.

Remember, the spell targets a point in space and not an object. Targeting a point in space touching the jar doesn't mean the bead will follow the jar.

In the end, putting it in a jar isn't going to give you the ability to move a spell effect that says that it stays put.

You can throw it, but you have to touch it and take the risk

If the glowing bead is touched before the interval has expired, the creature touching it must make a Dexterity saving throw. On a failed save, the spell ends immediately, causing the bead to erupt into flame. On a successful save, the creature can throw the bead up to 40 feet.

Putting it in a glass container will not allow you to dodge the risk that comes with the throwing clause in the spell. To throw it, a creature must touch it which then triggers the possibility that it ignites right there. If it is in a jar, you are not touching it, therefore you cannot throw it.

You can only extend the duration of the spell once

The rules for metamagic say:

You can use only one Metamagic option on a spell when you cast it, unless otherwise noted.

Extend does not provide an exception to this rule, so you can only apply it once to your casting of delayed blast fireball (see this Q&A for more details). That means the duration will be extended to 2 minutes for a hefty 32d6 of damage.

No.

You cannot carry it in a flask, but you can throw it. And the maximum duration is 2 minutes, not 17 hours. Here's why.

1. The bead of the fireball does not move. You choose a point within range when you cast the spell, and the bead stays there for the duration.

From the Delayed Blast Fireball description in the Player's Handbook:

A beam of yellow light flashes from your pointing finger, then condenses to linger at a chosen point within range as a glowing bead for the duration.

How the bead interacts with a flask is not specified by the rules, so it's up to your DM. But however it does, you cannot make the bead move. Except...

2. Anyone can throw the bead, but first they have to touch it.

From the spell description:

If the glowing bead is touched before the interval has expired, the creature touching it must make a Dexterity saving throw. On a failed save, the spell ends immediately, causing the bead to erupt into flame. On a successful save, the creature can throw the bead up to 40 feet. When it strikes a creature or a solid object, the spell ends, and the bead explodes.

3. You can only extend the duration to 2 minutes.

From the Sorcerer class in the Players' Handbook (the section titled Metamagic):

You can use only one Metamagic option on a spell when you cast it, unless otherwise noted.

So the maximum damage you can do with an Extended Delayed Blast Fireball is 32d6. That's a massive amount of damage even at the highest levels of play.