I used vapour barrier then a thin layer of this foam stuff for a bit of cushioning. Cheap and probably worth it.
I used both, but it looks like this stuff is a 2in1
https://www.homedepot.ca/en/home/p.u...000404555.html
I didn't have a mitre saw for mine (but I've helped my dad and he had one) so I used my table say which worked fine. If you built a jig you could use a circular saw if that's all you have.