Low cost seed starting cabinet

I live in Alaska and heat with passive solar and wood. This creates a lot of temperature variations in the house. I had limited success starting seeds indoors the past couple of years due to the lack of a place with a steady temperature, so i wanted to share the solution i came up with this year.

I made a little cabinet with scrap materials, and bought a digital temperature controller on ebay for about $11. I wired the temp controller into an extension cord. I plug one end in and the other is hot only when the temperature at the sensor (included with digital temp controller unit) drops below the temperature of my choosing. I have a few light bulbs plugged into this extension cord, so they heat up the cabinet and provide the plants with a bit more light, and then when the temp rises above a certain level, the controller switches the circuit off. (currently i have it set so the lights come on at 72 f and go off at 75 f. I cover it with a blanket at night so the light does not keep me and family awake.
each shelf in the cabinet is lined with plastic so no water can escape. this conserves water and avoids messes. I put bubble insulation on the sides never exposed to sunlight and clear plastic elsewhere.

This setup looks similar to what I have tried in the past. I remember having issues with a fungus on the soil surface. I thought it might have been due to a lack of air circulation. Have you had any fungal issues? I too have too many temperature fluctuations in my house. And limited space, and not enough light...

yes i did have issues with fungus on the surface and also lost quite a few tomato seedlings. there was also condensation on the inside of the plastic. i started keeping it open as it is in the last foto and there have been no new problems of this kind. I also had some tomato starts survive after this change in management and are beginning to thrive (subarctic 25 variety) but i also changed my potting mix to plain native soil (i was using a mix i tried to sterilize myself in a crockpot). even with the plastic open it still heats up enough that the light is not always on, even when its much colder than 72 degrees in the house.

My problem may have had to do with my soil mix ( i sterilized in a pressure cooker). This year I bought a soilless mix. With the setup, i considered adding a small fan but there was already alot plugged into one power strip.
For the past few years ive started long season veggies inside in March but my partner starts some in the cold frame in April and his passes mine. Might try it his way awhile. Need to do something soon.