One of the most used is the Secret Wooden or Iron Door camouflage door, it can be placed outside in your house wall or anywhere it may fit. You can combine the Camo TrapDoor that acts like a regular trapdoor but it looks like the surrounding blocks and nobody will detect that there is a secret trap. Once you installed the Secret Rooms Mod your precious items or secret rooms will stay hidden and protected at the same time.
One classical method that was used in games or even in movies is the Torch lever that looks like a torch but acts like a lever that opens your doors to the secret rooms or other kinds of places. The most important item of this mod is the Camouflage Paste, by combining it with different items from the game you are able to hide your base or whatever you want. Secret Rooms Mod adds a lot of new options that helps you to hide or camouflage the entrances to your hideaway or stash, by using the invisible switches to the hidden trap doors that can be placed everywhere in your house even on the ground.