5 ideas
In the workmanship of risk, the quality of the result is not predetermined and stays at risk at every moment, because it depends on the maker's judgement, dexterity and care as the work proceeds. In the workmanship of certainty, the result is fixed before making begins by jigs, templates, set-ups or automated machines, so the operator cannot spoil it through a momentary lapse.
Whether work is handmade or machine-made is the wrong distinction. What matters is whether the outcome is predetermined by a guiding device or left to continuous human control.
Design is whatever can be conveyed in words, drawings or specifications before the thing is made. Workmanship is everything the maker determines beyond that specification, including surface, crispness, precision and the quality of execution. Two objects built to an identical design can therefore differ enormously in quality, and that difference belongs entirely to workmanship.
No made thing ever exactly matches its design, so perfection is not an available standard. What exists is a chosen tolerance, meaning the degree of approximation judged good enough for the purpose. Seeing quality as a deliberately set level of approximation, rather than as nearness to an ideal, shows that 'precision' is a decision about cost and purpose rather than an absolute virtue.
The workmanship of risk produces subtle, unplanned variation between pieces and across surfaces within the maker's tolerances. That variation gives made things much of their visual and tactile richness. The workmanship of certainty removes this variation and yields uniformity, so its main loss is not lower quality but the disappearance of diversity from the made environment.