hi,
i've crashed my first 32" foam airplane few times, mostly face plant. and still learning.

Each time most of the damage was done to the firewall with inrunner motor causing shaft to bend and firewall to break.

At first i was cutting replacement out of thick balsa, but switched to cardboard.
Surprisingly it works well. It is also widely available, light, cheap, and easier to cut, absorbs damage, giving better chance of not bending the axle.
I used thick corrugated 2 layer cardboard from tv box. just dont forget to use large washers.
Fuselage is hollow with stryrofoam walls. these walls go around the firewall flush (originally was glued), so i just taped it with electrical tape. It's holding strong, much like balsa
Much faster and easier fix for those of you who is learning.