This Module is currently available.
case fan companion for the PAC BOT series of modules
pointandclicksystems PAC Systems
Aluminum or black anodized. Draws 5v power from the RPI GPIO or Lattepanda mainboard. I can also make them powered from the 12v rail with speed control at no extra charge (beware output voltages above 5.0 not recommended)
Create some forced air circulation in your case. Reasonably quiet and blows air on your face while you perform! It feels quite nice actually. Its a good idea to leave a couple gaps in your rack for the best performance. Also install on the upper tier to evacuate hot air and put your gaps in the lower tier.