We have collected all the materials we need to build a DIY incubator, and will begin putting it together soon.
We're using an old crafting cabinet, but other people have used insulated coolers (styrofoam too, though these don't make good brooders after the chicks hatch), large drawers, plastic storage totes, etc.
Want to build one too? Here's a materials list:
Some kind of container you can drill holes into and cut a window in, for the incubation box
A 12v fan from an old desktop computer, leave wires attached
An old cell phone charger or other 12v transformer that plugs into the wall
A piece of plexiglas or glass, about 9" x 12" for a viewing window
A lamp socket with cord
A light bulb (40w suggested; may have to adjust wattage to get temp to the right point)
Hot water heater thermostat (lower)
Thermometer and hygrometer
Pan for water as a humidity source, also jars filled with sand, pebbles or hot water to use as heat sinks
We also picked up a package of styrofoam insulation panels to insulate the cabinet, since it is made from thin boards.
You'll also need a drill and bits, screwdriver, keyhole saw for cutting the viewing window, electrical tape and/or wire nuts, perhaps some aluminum foil, and a desire to watch eggs hatch into chicks.
I included a photo of the cabinet as it is now. Regular updates to follow!