So, partly to get a wider base of advice and partly to let
@Shyft show off the mechanics of crafting some more...
Alrighty then: As precedent, you're going to want to brace yourself, and then crack open Dreams of the First Age: Lords of Creation.
On Book page 101, there is a sidebar called 'Making What Where', which gives some minor craft errata and summarizes the aesthetics and trappings of some craft actions. It's nothing comprehensive though- the full artifact creation rules are in Oadneol's, and then Magitech-Repair Rules are in Wonders of the Lost Age.
Now if you double-back, there's another sidebar on page 96 titled 'Upgrading Artifacts'
"Improving an Artifact starts with the same process as designing a new Artifact. Once construction begins, however, the design requires fewer exotic materials than normal (with a difference equal to the former Artifact rating) and similarly reduces the number of cumulative successes needed to build it in its former state. Using this process, it is possible to join seemingly unrelated designs to spectacular results. For instance, a Goremaul refitted with qualities of a Perfected Calculation Array might become an intelligent weapon that teaches and guides its owner."
So
parsing that:
Design:
You need dots in Lore, Occult and Relevant Craft equal to [Rating +2]. (So the 3 dot minimum is for art 1s). As well as [Art Rating +2] in Resources.
An Artifact Roll is divided into three stages. Theory, Experiment, Construction. The first quarter of the successes can be done in full theoretical- as thoughts or notes on a page. The second quarter must have a lab or workshop to perform experiments and create prototypes.
For both the theory and experimental stages, You make a number of craft rolls at [End Artifact Rating +2] Difficulty
Every 5 successes earned at the theory and experimental stages means the Storyteller should tell you in a sufficiently quest-bait sort of way what components you need to make your artifact.
Once you've accumulated half the cumulative successes required by a project, you move on to gathering the components. The artifact is now a set of completed plans and can be copied off to someone else too if you want. (This means they don't need to do design rolls, but they still need the exact same components you do).
Once you have [Artifact Rating] components, you go back to the workshop and finish rolling to complete the artifact.
In the case of UPGRADING artifacts, I'm THINKING you have to DESIGN it all the way from scratch, but then you treat the 'prior' artifact as hacking off a number of cumulative successes derived from it's rating. The exact number needs a bit of elaboration...
So interpretation 1: Design is More Important
Building an art 4 normally requires 100 successes. 25 theory, 25 experiment, 50 construction. and 4 exotic components. Upgrading an artifact 3 to an artifact 4 requires 25 theory, 25 experiment, and then 50 minus [half of whatever an art 3 would require to construct, 30 succesess in this case]. AND only one new component.
Interpretation 2: Easier Math
Art 3 into Art 4 requires 100 successes - 60, leaving 40 left over. 10 Theory/10 Experiment/20 assembly.
Not sure which provides the superior advantage or fits the playstyle better, but that's your baseline.
Artifact 1 - Diff 3, 10 successes, 1 component, lore/occult/craft 3
Artifact 2 - Diff 4, 30 successes, 2 components, lore/occult/craft 4
Artifact 3 - Diff 5, 60 successes, 3 components, lore/occult/craft 5
Artifact 4 - Diff 6, 100 successes, 4 components, lore/occult/craft 6
Artifact 5 - Diff 7, 250 successes, 5 components, lore/occult/craft 7
In the inevitable case of upgrading an artifact without changing it's rating, I'd basically say you'd have like, a minimum of 5 successes at any given phase of the project. More likely 10.
