Air flow and component placement

I am incorporating my PC components within my desk drawer with a perspex screen cut into the top with fans pushing and pulling from opposite sides.
My question is: Can I simply place the components (mobo, graphics card, etc) on the 'floor' of the drawer, or do I need to raise it off of the surface? If so, what materials should I raise it with and can I simply lay the Mobo (for example) on top of the raised surface? Or am I at risk of shorting it??

Is the desk draw metal or wood?

If wood, you can lay it in the draw with no issues.

You may want to lay it on an anti-static mat though - "just in case"

Anti-static mats are conductive. That's how the draw the static out. The silver outside and pink bags are the same. Do not put energized circuits on an anti static mat, it's for soldering and other non-powered repair uses. Just use cardboard if it's a metal bottom. Or put the standoffs from an old PC case on the board and lay it like that in there.