They bump together... and that still didn't help you realize the problem with what you're doing...
Maybe.... It would probably take about 5 minutes to go find a plastic ruler or similar thin piece of material. Pop a few holes in it and use the existing mounting brackets and screws to build something somewhat structurally sound that isn't going to destroy good equipment and/or cause a fire.
Or.... use plastic chains and spread the equipment out on plastic hooks until it looks like the final scene in the first Hellraiser movie. Stick a paper banner saying something like, "AMD wept...." Now you have functional art.
Or.... get a case. If your cards don't fit in one case, get two cases. A lot of cases (especially Antecs) allow both side covers to be removed - you could remove the side that usually is on the solder-side of the motherboard and mount the card inside the case with any PCIe extender cables stretched over into the next case. Duct-tape them together side-by-side and use them for a spare bench.