Wood is a poor conductor of heat. So attempting to use heat cord to outside a melamine enclosure is ineffective and wasteful. The neat cord needs to be inside the enclosure.
An alternative to do it is to use a base of thin MDF, about twice the thickness of the heat, and same shape as the tile. Cut grooves to the thickness of the cord parallel across the base then a few at each at right angles to the others. Ensure grooves are wide enough to allow the cord to move freely around corners. A simple hand saw can be used to do this. The end 3 cm of the cord is thicker than the rest. This can either be left protruding from the tile or simply expand the section groove where it is to fit. Then use a sealer to make the base waterproof. Using dobs of Blu Tack the tile can then be firmly, but not permanently, fixed to the based. The only permanent cut in the enclosure is a small hole in the back corner, or side, just big enough to thread the heat cord through.
Ceramic of late tiles are much better conductors than wood, but nowhere near as good as metals. The plus side is that by the time the heat is conducted through the tile, it has evenly spread out. Tiles also have a fairly high’ specific heat’, which is the amount of heat required to raise their temperature by 1oC. So while they are slower to heat up, they are also slower to cool down and will therefore maintain stable temperatures. The MDF base acts as insulation and enables the majority of the heat produced to be transferred into the tile.
This provides a moveable heat tile when cleaning. It is can also be shifted for use in a different enclosure. It is easily re-adjustable for temperature by changing how much of the active heating section of the cord you allows to hang outside of the enclosure.
PS I did write a similar post and thought i had posted it, but apparently not. So I have re-written it (ans saved a copy this time lol)