we call that "Bondo" (a brandname) and yeah it has some fans but...if this was my frame and I wanted a "no-heat" method I would use epoxy putty. There are many colors (if you go to wood/furniture repair sources) but the typical one sold in hardware shops is gray.
I think it's a stronger "patch" than Bondo.
But Do The Prep (roughen surfaces and clean with denatured alcohol) to optimize bonding.
If you shop around (and if it matters) you can find epoxy putty in white, I know Mohawk and maybe Behlens sells a tube in that color.