stacking components without leaving marks

Paper works. I assume that you are going to use stock rubber feet. I stock components too, but I use different feet under each component; the difference in sound when using good feet is quite big.

Elizabeth, this is not that simple. You forgot vibration. Rack can make it better or worse. I experimented a little with various feet and cones. So on the bottom of my "stack rack" is a MDF platform, soon to be replaced with something else when I figure out or guess which one would be better, that sits on four Mapleshade Isoblocks 2, then Acoustech phono stage is on the platform with 3 1.5" Audiopoints under it, then Nakamichi deck is on top of it with three Polycrystal feet under it, and finally Audiolab integrated is on top of everything with three Boston Audio Tuneblocks under it. The whole thing is on hardwood floor.
Turntable and CD player are separated from this and each other.
Deck gives the most vibration, but of course I never use it at the same time as the phono stage. When I make recordings, not too often, I disassemble my pyramid and everything is separated; I also unplug all the equipment except what I use for that and monitor the recordings through the deck's headphone jack.
I used cheap racks before and it was much worse than what I have now.