10 x Stackable 3.5 Inch Hard Disk Drive Mounts with 12x12cm Fan Attachment Holes
I used 5 x WD100EFAX to design and test these mounts. A 120 x 120 x 25mm Fan can be mounted every 4 or 5 drives. If you add a fan every 5 drives there will be a 13mm gap between every fan. 120 x 120 x 25mm Fans.