Bridgenorth actually made his own. Unfortunately, he sold his Micra this spring so he's not around anymore.
The trick is (I believe) you need a custom MAF housing. Bridgenorth made his own: he bought an extra part where the OEM MAF is located and cut it out, epoxied it into the new part & bolted on some generic eBay tubing & filter.
Tim (Daox) does design work and 3D printing, and has made custom MAF sensor housings for other cars. If someone wants to work with him, he'd make up a design that could be made to order for a good price.
View my fuel log 2015 Micra S manual: 5.0 L/100 km ... 56.5 mpg (Imp) ... 20.0 km/L ... 47.0 mpg (US) ...