Tinkering
When an Artificer wishes to modify weapons, armor, or tools, or invent new ones, they must follow these basic steps: DESIGN, PROTOTYPE, and BUILD. The time required for each phase and the difficulty associated with the task depends on the desired outcome; building things granted by the Artificer class will have a low DC, while novel, potentially game-breaking inventions will be very challenging indeed.
At each step, one or more skill checks will be assigned by the DM. The Artificer must complete all skill checks in one phase before moving on to the next. Critical successes count as two successful checks; critical failures wipe out all progress in the current phase.
Any skill may be used, provided the Artificer can justify how it applies to the current phase. The DM may adjust the difficulty depending on the approach.
An ally may help the Artificer complete a DESIGN or PROTOTYPE phase by lending their relevant expertise to the work; at the DM's discretion, the Artificer may be granted advantage on one or more skill checks.
An ally can only collaborate on the BUILD phase if they are proficient in artificer's tools.
Tinkering Phases
Design
The Artificer must provide a project estimate to the DM. For example, This is similar to an invention I have previously made, so I think the effort will be low, or, I want to invent laser rifles, so this will be difficult. The DM will assign a DC and a number of skill checks, typically Intelligence, required for a successful design. Each skill check in the DESIGN phase requires two hours of concentration.
Prototype
Once the Artificer has completed their design, they must now PROTOTYPE it to reveal any flaws or shortcomings. This will require a minimum of two skill checks:
- One Artificer's Tools Check; and
- One Skill Check related to the purpose of the item.
Each skill check in the PROTOTYPE stage requires two hours of concentration.
Build
Once the Artificer has completed a design and a non-functional prototype, they are ready to build their creation. This step requires:
- One Artificer's Tools Check;
- One Skill Check related to the purpose of the item;
- Any necessary material components, which are consumed by the build attempt.
Each skill check in the BUILD stage requires four hours of concentration.
Rebuilds
Once an invention has been built once, the Artificer may repair a damaged item or build another by completed the skill checks of the BUILD phase. The artificer has advantage on all checks for a rebuild.
Research and Development
An Artificer may spend four hours of concentration studying relevant blueprints, designs, ancient texts, to permanently reduce the DC of one skill check in any phase of development.
An Artificer may also spend fours hours studying an existing object to learn the intricacies of its design and reverse-engineer it. Doing so will allow the Artificer to automatically succeed one skill check in the DESIGN phase.
Example: Clockwork Flamethrower
DESIGN: 1 x Intelligence checks (DC 13). Minimum 2hrs.
PROTOTYPE: 1 x Artificer's Tools check (DC 13) to construct the mechanisms, 1 x Strength (Athletics) (DC 13) check to forge external housing that won't explode. Minimum 4hrs.
BUILD: 1 x Artificer's Tools Check (DC 10), 1 x Strength (Athletics) check (DC 10), disassembled parts of a clockwork dragon. Minimum 8hrs.
Total elapsed time, assuming no failures: 14 hours.