"I invent Greek Fire!" and other PC shenanigans

[Umbran]

Ah but bat guano is a negligible cost material component, you can spend 25gp and have an infinite supply of it.

No.

25 GP buys you a pouch. Then, an unstated bit of your upkeep costs each month go into keeping that pouch filled with the small amounts of it you need to cast spells.

Otherwise, 25 GP gets you a dozen guys and one person with half a brain to watch over them to dig around in a cave for a week. If the cave you chose has guano in it, and that guano decaying hasn't left the cave without oxygen, you get what those guys can dig out of the cave in a week and carry back to you.

Congrats - 25 GP has gotten you a pile of guano. Now you have to process it....

And you get about 4 lbs of saltpeter from each hundred pounds of guano.

And from that, you'll get... 2 to 4 modest canon shots.

But, of course, you haven't invented the cannon yet...

 

[Umbran]

Levers, pulleys and the like should also not be too hard...

You figure they built all those castles without levers and pulleys?

So, how'd they move all those rocks? Was it... aliens elves or something?

 

[Bagpuss]

You figure they built all those castles without levers and pulleys?

That was my point, that sort of stuff is readily available at the sort of tech level of a fantasy setting.

 

[FitzTheRuke]

How is that not just Alchemist's Fire (available in most D&D Editions, and usually not all that great compared to spells)?

 

[FitzTheRuke]

Also: I'd like to see them make Greek Fire, or Gunpowerder in the real world. They think they know how to make it, but they really, really don't.

 

[FitzTheRuke]

"Okay, your character leaves the party to take the three to five years (truly generous DMing) that it takes them to figure it out, assuming they survive. Are you now going to roll up someone who wants to go on THIS adventure?"

 

[Fenris-77]

I'm going to write the long and nuanced answer. No. No, you bloody don't.

 

[Koloth]

Player knowledge not always equal to Character knowledge. Even if the player wants a character to invent something, the character first has to get the idea for that invention. (Inspiration check.) Also, many inventions depended on prior inventions. Greek fire may have required prior inventions over several generations before the first Greek Fire round was deployed in combat. The time between gunpowder and firearms was several generations. It took Edison thousands of failed attempts before a practical light bulb glowed. The Wright Flyer didn't happen until the new fangled internal combustion engines were light enough for the power generated to allow the plane to fly.

Even if a character gets inspired, does it have the funds, workspace, time to work on the invention? Someone working on Greek Fire or Gunpowder might well irritate the neighbors. "Deputy, he caught my chicken coop on fire yesterday! And the smell! Makes an outhouse seem downright nice! It is demons I say, DEMONS!"

 

[MichaelSomething]

What level are the PCs doing this???

 

[Cordwainer Fish]

Also: I'd like to see them make Greek Fire, or Gunpowerder in the real world. They think they know how to make it, but they really, really don't.