I have used both komatex and komacel My bearded dragon enclosure is made from Komacel and multipanel (aluminum clad PVC) It works well. The komatex I used was a few years ago now it is a bit softer and a little easier to bend. It also is fine. I understood out gassing occurred at beyond 95ºC (203ºF) mine never ever approaches this, even 70ºC is 158ºF. The hazards of PVCx usually come into play when the material is being cut and machined not during use. Why is is used in food grade applications as well.

Melamine has a handful of hazards that are 24/7 for 10+years regardless of temps. The out gassing of formeldahydes pose a risk to humans and likely animals as well. The new (low formeldahydes) replace urea formaldehyde glues with phenolic resins that leach phenols that reptiles are HIGHLY sensitive to. The cutting issues are more pronounced with particulate substrates of melamine boards. melamine toxicity has been an issue in china during the last ten years and the US FDA dropped the allowable limits by 100 times as a result. The additional issues of moisture and melamine substrate make disinfecting correctly a challenge. Saturating the built object, liquid gets into any and all joints that can cause swellling and cracking.

No komacel cannot easily be painted. It will take well to printers inks but in my experience paints do not work well. I might look at buying vinal intended for sign cutting in rolls and apply it. The range of colours is almost unlimited. It also is not a soming that requires aging like paint does.