Q:

What to keep on the wooden table to make the surface heat resistant?

Oven manual says - keep it on a heat resistant surface. 
I have a wooden table. What should I keep on the wooden table to make the surface heat resistant, so that the oven can placed on the top of it?
Paper sheets won't work? Thick cloth?

A:

When we had a wooden table as a child for every day use, we kept a layer of tempered glass that sat up on silicone feet so there was a thin air gap between the table and the glass. The glass covered the entire surface of the table, so there was no risk of spills or hot items damaging the actual wood surface of the table.
I would look into something that definitely had an air gap below it. A stone, ceramic, or glass cutting board (or a tile tray) with feet would work. 

A:

Something like a granite or other stone tile might work.
But if the oven has legs, then it is probably fine just standing on the table. I'm thinking of a regular household toaster oven.

A:

For your purposes, I'd get a wood or bamboo cutting board of and appropriate size, and keep it underneath.  It might get a little heat scarred from the toaster, but it won't catch fire, and it will protect the table.

