Insulbright is what I use.

I use worn out mattress pads. Cut the good parts to any size you like and can make any thickness you like. You just have to remember they need to be foldable to wrap around handles.
My favorite size is oblong.

I use two layers of Insulbrite.

I
f you know where to get truck inner tubes they are wonderful.
Sandwich them between 2 pieces of material 1 inch larger than the cut tube sew around as close to the inner tube as possible then cut around as for a rag quilt and they work as hot pads as well as pot lifters.

They are potholders, so I would guess this is where I must store my pot. Let's see though; I don't have any pot. Therefore I do not require a potholder.

In the home I grew up in they were called hot pads. Any time I have ever made a hot pad, I used the remnants from a mattress pad. The bottom was a piece of denim fabric from an old pair of jeans. The top part could have been remnants from Aunt Bessies dresses (after we removed Aunt Bessie).

The very best and safest is an ironging board cover. Use the fabric and backing. It is great insulation

I put polyester as a sandwich for two layer of cotton stretch like old pyjamas or t-shirts then the top and baking and yes i quilt it to feel secure when hold.

I have been using some commercial ones for a couple of years and recently scorched one and washed it! Eeuuuwww!
It is full of red cow hair. Being a farmers daughter that doesn't bother me so much, because, by golly, they were very good thick heavy potholders! It worked very well.
The point is - WE make better ones!

Ditto and I use a layer of batting also.

I prefer using Insulbrite, also.