Zappo
Explorer
Well, everything I wanted to say has been said while I was checking the spells' descriptions...
Manufacturing items while the material is reduced wouldn't work that well; any metal stress or other factors mentioned by Chimera would be multiplied the moment the spell is gone. You would end up with a very brittle material, which is unlikely to resist the pressure of a steam chamber for long. This has nothing to do with finesse in working the material, it's a physical thing which depends very little on the artisan's skill. I think modern steel melting techniques might work, as well as very high temperature ovens, but I doubt any of that is available to your elves. Even then, the material would still be far inferior to its mundanely-forged counterpart.
Additionally, you would need very skilled artisans, able to craft small items. This is a skill very different from the one your current metalworkers know, so you would need to train them all in miniature working, or fire them and hire others.
Loading a ship with lots of extra goods (or powder, shots or whatever) beyond its capacity means that an area-effect dispel magic will immediately sink it. That's a very nasty vulnerability and not one I'd want on my ships.
The tactic of dropping shrunk items from high can work but, again, it makes the wizard extremely vulnerable to a dispel magic spell. While the fly spell doesn't make you plummet if dispelled, you will plummet if you are suddenly carrying a load beyond the spell's limits.
If you really want to stop the thing before it even gets tried, you can rule that a reduced item is magical, thus preventing use of shrink item, or that shrink item will be dispelled as soon as enlarge ends because its target is no longer valid. Both are perfectly acceptable rulings.
Still... magic in D&D can do nasty things to a campaign world if it is applied with a 21st-century mindset. The coherence lies in the fact that usually, people in a medieval fantasy world just don't think like that, and in that wizards are rare and have many better and better paid things to do than working as carriers.
Anyway, take a look at the DMG where it states the prices for NPC spellcasting - most industrial applications of magic would become overcostly very quickly.
Manufacturing items while the material is reduced wouldn't work that well; any metal stress or other factors mentioned by Chimera would be multiplied the moment the spell is gone. You would end up with a very brittle material, which is unlikely to resist the pressure of a steam chamber for long. This has nothing to do with finesse in working the material, it's a physical thing which depends very little on the artisan's skill. I think modern steel melting techniques might work, as well as very high temperature ovens, but I doubt any of that is available to your elves. Even then, the material would still be far inferior to its mundanely-forged counterpart.
Additionally, you would need very skilled artisans, able to craft small items. This is a skill very different from the one your current metalworkers know, so you would need to train them all in miniature working, or fire them and hire others.
Loading a ship with lots of extra goods (or powder, shots or whatever) beyond its capacity means that an area-effect dispel magic will immediately sink it. That's a very nasty vulnerability and not one I'd want on my ships.
The tactic of dropping shrunk items from high can work but, again, it makes the wizard extremely vulnerable to a dispel magic spell. While the fly spell doesn't make you plummet if dispelled, you will plummet if you are suddenly carrying a load beyond the spell's limits.
If you really want to stop the thing before it even gets tried, you can rule that a reduced item is magical, thus preventing use of shrink item, or that shrink item will be dispelled as soon as enlarge ends because its target is no longer valid. Both are perfectly acceptable rulings.
Still... magic in D&D can do nasty things to a campaign world if it is applied with a 21st-century mindset. The coherence lies in the fact that usually, people in a medieval fantasy world just don't think like that, and in that wizards are rare and have many better and better paid things to do than working as carriers.
Anyway, take a look at the DMG where it states the prices for NPC spellcasting - most industrial applications of magic would become overcostly very quickly.