I wanted to add a bit to the account of Chuck's rifle hide behind wall paneling. I am a cabinet maker and have spent more than a few hours puzzling over the various problems and pitfalls of concealed storage. Several are present in Chuck's solution.

While I do not like Velcro (as it wears out, accumulates litter and makes noise) if dots are to be used,  (a) raw wood tends to shed self adhesive material such as is common to these dots and (b) one needs to account for the thickness of the Velcro hook and loop sandwich which will cause the removable panel to be proud of its neighbors. Finally we need some way to grasp the panel easily to remove it once it is all setup, since repeated prying or levering can scar it.