Material that allows later modification by heat

[curious aardvark]

yes there is. basically any filament will do this - it's what the word
'plastic' means :-)

But what you probably want is something like this: https://ooznest.co.uk/product/skulpt...lament-1-75mm/

PCl is the stuff: Polycaprolactone
The 3d scan is the hard bit :-)