I really like Leo Gray's "easier remix" of the OpenGrid Removeable Command Strip Mount, but for attaching adjacent panels, I wanted the ability to snap a single mount into two adjacent grids. The closest thing I could find stretched across 3 holes rather than locking into two adjacent holes.

Here's my solution. It's a tight fit, but it works. There's a quad version at https://www.printables.com/model/1553632-quad-command-strip-mount-for-opengrid

Use Leo's hand tool (not included here, as I didn't change it) for easy opening and closing.