Hot and cold spots are not such a problem when you use an old fridge or freezer to begin with because they keep the majority of the thermal gradient in their walls, rather than in the eggs, which is what happens with lesser incubators. The less insulation you have, the more heating power and fanning is required to attempt to push back the start of the significant part of the thermal gradient.
Help needed on dyi cabinet incubator - Page 4
The design of the cabinet is a tried and tested method that works. Just look at gfq incubator cabinets which are the standard for large home use incubators. This is not about efficiency or an easy build this is about making a incubator that looks good.
I tend to use wine coolers as I lack wood working skills and they are easier to work with as long as you except that the size is fixed. This makes adding or building a turner the harder part of the job. As i like the more modern industrial look stainless steel wine coolers are my personal preference. I have seen some home built incubators in wood that not only work great but also look amazing. I can honestly say I that I have never seen a mini fridge, fridge, freezer that I like just for the way it looks.
well, if it IS all about the wood look on the outside, cool. To get that temperature a bit better and evened out, it would be a good idea to line the inside with metal foil. Aluminum foil, or builders foil which goes under the roof tiles. In some places it's called sarking. You could more easily find a reflective sun shade for a car and cut it and line the lower parts of the incubator to bring the temperature up.
The better insulated the cabinet, the more abruptly the thermal gradient changes at the cabinet wall, rather than throughout the cabinet as it is now.
Also, if you want fantastic looks, something that you can look at, that does not rule out a fridge to start with. Commercial glass front fridges would give you a working incubator which you can admire the eggs through without opening the doors. LED lighting to illuminate the eggs and so on, I can't imagine how it could look better. I expect it may have been done before.
Yep, quick google, it's been done before and those wine coolers are quite popular, I think that would be because of their small size.