which fan for a DIY incubator

[Sphynxcrazy]

theres this place close but I might get the CPU fan from, except which one do I need?? The inside measurement of the strofoam box is 13'' by 15 and a half inches.

Which fan size or specific fan or what do I need?? I found them for 4-5 dollar on here. http://www.thefanvan.net/servlet/StoreFront

The chest/box doesn't have a lid but I do have a thick piece of styrofoam I can use maybe, Just I am wondering because the chest is a bit beat up around the edges.

 

[sumi]

We used a little PC fan in our home made incubator and it worked fine.