Use wallmounts from Open Armory: https://www.printables.com/model/413796-open-armory with MDF slatwall/slotwall panels.
Access to the edge of the panel is necessary, these are slid in from the end. Two widths provided, full and half width. You can just use two of the half-widths if space is limited.
Currently only tested with ‘single-rail’ mounts (magazine holders), spacing does not work with ‘dual-rail’ mounts (like for rifles).
The author marked this model as their own original creation.