What is the type of foam used for bracing batteries in rc cars? Does anyone know where to buy a large block of the same or similar material?

/ by large, I mean 3"x5"

I know it's not exactly answering your question but when I needed to make a custom foam spacer for a buggy that didn't originally account for shorty batteries, I would just buy a few of the Associated SC10 battery spacers and cut/glue together to make it work.

https://www.amainhobbies.com/team-as...asc9815/p36988

Funny thing, but I kinda came to the same conclusion as you did (after posting, of course).

I think I'll pick up a RB6.6 battery sponge. It's designed to separate into various depth foam blocks. I'll have to do some cutting and trimming and then hot-glue the frame together. Should work, might be a little ugly.

As long as it works and keeps your battery safe, looks don't matter lol.

I use anti fatigue mat.

I also use anti- fatigue mat. Harbor Freight sells a 4 pack of 2 foot by 2 foot squares with puzzle edging for $7

Anti fatigue mat is a good idea. Tool foam works really well, too.