30mm Fan Adapter for Rostock Max V2

Allow for the use of 30mm fans on the layer cooler. Rather than replace the ducts, this allows you to replace the box fan with a standard 30mm fan (Like the ones used on E3D peek coolers) as a temporary fix until new box fans can be purchased.
Mount a 30mm fan and insert into the duct.

I had several 30mm fans in stock when I built my Rostock Max V2 and wanted to have full layer cooling. The layer ducts I found on line were either for 40mm fans, or were too big to fit when using an E3D hotend