How much should it cost?

[Climowitz]

I want to make a custom item that uses Fabricate the spell as a crafting box. But the catch is that it would only be useful to craft a defined object nothing else but that. So a custom magic item of Fabricate at will should cost 90k GP and would be usable to craft anything (I know it needs the check beaten) given the restriction that it can only create a single item, what would you make it cost?

My dm ruled it at 60k gp I thought it was still to high and went for the full one. But I would like different opinions to measure both our points of view. I would have made it 10k.

[Jack_Simth]

Answer varies wildly. Custom items, especially those with custom limitations, are up to DM whimsey.

I might note that potions explicitly require all aspects of the spell be selected at brewing time, and that doesn't affect the cost of a potion of Energy Resistance.

[ExLibrisMortis]

It depends on the item you're crafting, especially the skill rank requirement, and the activation cost. If it crafts based on the user's skill ranks and requires the same activation time as casting (i.e. one round/unit of volume to be affected), 10k is reasonable. If it crafts autonomously and has its own crafting ranks, a higher price is appropriate, but probably still not 60k, in my opinion (unless you're crafting more-than-masterwork items). Maybe 20k or 30k.

[Biggus]

Do you have a particular item in mind that you want it to make? If so what is it?

[Crake]

Well, if the box in question is cumbersome and difficult to move around, then that warrants that it be classified as wondrous architecture, and as a result, an automatic halving in price. If it is actually built into it's location and cannot be moved without risking serious damage to either itself or the structure it's a part of, then that warrants another further halving in price, to a starting price of 22.5k.

For the sake of argument, I'm going to assume it's merely cumbersome to move around, so we'll start at 45k automatically. If we assume that the box crafts these items itself, then I would say that the price increase would be simply the cost of an intelligent item with 10 ranks in craft (allowing take 10 for 20, which achieves masterwork level crafting, generally the highest DC for craft skills), which comes in at a +6,000gp increase, though if we make it so the box is literally only capable of that singular task, and has no other use for it's intelligence, that would more than easily warrant a halving of the intelligent item price. This brings our newly minted crafting box to 48k (or 51k if your DM doesn't let you reduce the cost of the intelligence). But now comes the conundrum. This box is capable of crafting ANYTHING currently. Now how much of a price reduction would it be worth to reduce that functionality to just a single thing it can craft? That would be the hard decision to make.

Personally, I think for something that has infinite variations in it's use, the best place to look is actually the charges per day. If 1 use/day costs 1/5th of the cost of an infinite use/day item, then I think a 1 variation item would appropriately cost 1/5th the price of an infinite variation item, which would place the price somewhere around the 9-10k mark, interestingly quite close to where you priced it to begin with.

[Climowitz]

The idea behind is I'm kind of making an industry with magic. I'm building a radio but in ravnica to control the media to fight dovin bean on the azorius Senate, this box would look like a conveyer belt and the box is where magic happens raw material comes in and the full product comes out. Dm allowed that a single fabricate would create all the components but it would have to be assembled so I'm also using unseen crafters to do the work.
I had no knowledge of that price reduction for it being a wondrous mechanism or bound to a defined space, where are those from?
The item being craft would look like a radio, a simple reciever to emit sound of someone talking. We are not considering radio waves but instead think of the item attuned to the "antenna" that would emit the signal. Since is not a magic item actually raw materials cost only 3gp.

[Crake]

The idea behind is I'm kind of making an industry with magic. I'm building a radio but in ravnica to control the media to fight dovin bean on the azorius Senate, this box would look like a conveyer belt and the box is where magic happens raw material comes in and the full product comes out. Dm allowed that a single fabricate would create all the components but it would have to be assembled so I'm also using unseen crafters to do the work.
I had no knowledge of that price reduction for it being a wondrous mechanism or bound to a defined space, where are those from?
The item being craft would look like a radio, a simple reciever to emit sound of someone talking. We are not considering radio waves but instead think of the item attuned to the "antenna" that would emit the signal. Since is not a magic item actually raw materials cost only 3gp.

Wondrous architecture rules are in the stronghold builder's guide.