Having a character run parkour in a battle is such a cool gaming element, but it never translates to mini terrain as well. The character is padding along a rooftop while the mini is sitting on a pedestal normally used to indicate someone flying.
Another thing that irritates me with most carrying trays is that the minis can fall right off. Pieces have snapped off my top-heavy Rotten Belles as they wobbled right off the tray and shattered on the floor.
So I decided to make carrying trays that could double as terrain pieces. And for my terrain pieces, I would drill holes to glue in rare earth magnets. Then on each miniature, I would get a piece of metal glued to under the base.
An example on the terrain: Warlord's Ruined Hamlet has a gable on each side to place a fallen roof. The divets there are large enough to put a rare earth magnet, so I used some green epoxy to secure the side not receiving the skeleton of the roof.
Meanwhile the "skeleton" roof has a few hidden magnets of their own.
Similarly on the trays I drill a hole for the magnet.
Of course all the magnets wont work without some metal to secure the bases. I tend to favor washers, but they need some room. The plastic tabs underneath get in the way.
A Dremel will take care of routing out the interfering tabs.
Final step is a little green epoxy and the washer. I like a fat washer (3/16" x 3/4") so the magnet has a better chance of making a connection. You can pick these up loose at Lowes - part number 61697.