Happy to see you moving on to the preorder phase, Josh.
And I'm terribly sorry that I totally missed your suggestion at the end of your post back in August:
Maybe it's too late and you have since already tested other CPU coolers <40mm tall in addition to what you had done earlier, and have confimed that every one of them with linear directional air exhaust trail the Zalman CNPS2X with its omini-directional air dispersion in cooling performance. If you still would like to have more data, though, I'm happy to contribute whatever test results I could perform on my own once I decide to purchase your work of art (when that happens I probably try to grab CNPS2X and test it too as a reference). My collection of "low profile" air coolers, though, haven't seen any update for quite a while, and these are all I have now (apart from some GPU coolers repurposed for Thin Mini-ITX boards that aren't in this photo):
(
Additional photos taken in different angles)
Among these, Scythe Kozuti (a close call and not 100% sure), Cooldesk Leishen ITX90, Titan TTC-NK52TZ (AMD only), Thermaltake Slim X3, Noctua NH-L9i, Titan DC-155A915Z, Thermaltake CLS0011, Cooljag JAC7L07C, Reeven Vanxie, Thermolab LP53 (with a <12mm fan replacement), and Gelid Slim Silence i-Plus are no taller than 40mm. I think some of them have already gone EOL so not so useful when it comes to recommendations.
I have been interested in Titan TTC-NC25TZ, Thermolab ITX30, and some of the relatively new coolers such as Silverstone AR05, Jonsbo HP-400 (and HP-200), ID-Cooling IS-VC45 and IS-40Pro (the last two will become about 40mm tall once their stock fans are replaced with a 10mm thick fan, forcing the fan size to be 80x80mm or smaller) but haven't purchased any of them. (I know Aiboh gave IS-VC45 a shot.) ID-Cooling also has omini-directional-fin LP coolers a la CNPS2X in their lineup.
Back on topic, I noticed on your preorder page:
Either one of the depth numbers are probably mistyped as they can't be identical?
Also, about the custom powdercoating option... I'm wondering if hairline brush surface + anodizing instead of powdercoating with a durable matte black textured finish on the exterior panels is an available option.
Oh, and I totally forgot to ask this before writing the cooler stuff above: the 40mm cooler height limitation is for the entire cooler including whatever fan on top, and does not exclude the thickness of the Scythe Kaze12-Slim fan you have in a few of your photos, correct?