Method
Built, not copied.
Every typeface starts as a set of parameters, not a scan.
Geometric and mathematical first principles
Every letterform starts as output from a parametric design language. Parameters set proportion, stroke contrast, and construction. Artistic judgment takes over from there, adjusting curves and spacing until the shape reads right at text size. No step in that process involves tracing a specimen sheet or reconstructing a scan — the outlines are an independently constructed design.
Historical specimens do get consulted, but only to check proportion and genre fit once a design is underway. Checked against period specimens for proportion: yes. Built from a scan: no.
Reference, not source
Historical type movements inform the design brief as philosophy, not as material to copy. The Bauhaus's geometric construction of letterforms and construction-by-grid type design more broadly were themselves early instances of parametric, math-first type design — long before anyone had a word for "parametric." The continuity Cast Iron Type draws on is in method, not look: the same underlying idea, run through modern tools.
Neomodette is the clearest example. It's a geometric sans in dialogue with Futura and Bauhaus modernism, built from first principles rather than reconstructed from either one.
Purpose-built tools
The foundry writes its own tools rather than working entirely in off-the-shelf font editors: a custom design language for specifying letterforms parametrically, and custom-built editing software to work in it. Building the tools takes longer than learning existing ones would. It's also the only way to keep proportion and construction consistent across an entire typeface family, rather than eyeballed glyph by glyph.
Scope stated plainly
A character set page lists what's actually finished, not what's planned. If Cyrillic coverage is in beta, the page says beta — it doesn't get folded into a glyph count that makes the typeface look more complete than it is. A specific claim you can check beats a vague one that sounds impressive.