<p>I've observed printing PETG that the primary if not the only reason for using a high bed temperature seems to be preventing the bed from acting as a huge heat sink and rapidly cooling the initial layers such that they don't bond well to each other. In particulat, the heat is not needed for adhesion-to-the-bed purposes. This got me thinking whether there's a way we could get rid of the requirement, as a way to save time and all the energy spent heating the bed and cooling the room it's eventually dumped into.</p>
<p>With that in mind, are there viable bed materials that are good thermal insulators? Just putting down a layer of any insulating material between the underlying bed and buildtak or whatever surface you want might work, but I would think these kinds of print surfaces are designed for moderate to high thermal conductivity themselves, and wouldn't be as bad a heat sink as the underlying metal, but might still sap a noticable amount of heat out of the part right away.</p>

I’m pretty sure it can be brought separately but usually comes with a lot of heat-beds; It is a type of foam that has adhesive on one side and aluminum foil on the other.
Here
is an example of what I mean: