I purchased a Pelonis oil-filled heater last year from Home Depot; works great, and it was on sale for 1/2 off 15.00. I also bought a Honeywell oil-filled, which I found at the Goodwill for 10 like new. The oil-filled are great because theyre quiet you can set the controls to go on when the temp gets too cool. is less than 0.5 mm, although it depends on kinds of material, swell of the surface is apt to be large, strength, namely durability is insufficient, and production thereof is difficult. If the thickness is more than 5 mm, it is difficult to raise and lower a temperature rapidly. As for the ceramic heater
