Instructions
Open the Roblox Studio application, then drag your ̶0;Roblox̶1; character from the Explorer window onto the main stage window of the application.
Click the ̶0;Insert̶1; option in the top menu, then select the ̶0;Free Models̶1; option. Choose any brick from the Explorer window, then drag and drop it onto the stage.
Click the ̶0;Tools̶1; option, then select the ̶0;Weld̶1; option and click the ̶0;Anchor̶1; option. Select the brick and place it into the bottom corner of the doorway of the room where you want the one-way door. Once you place the brick down, it will anchor itself in position.
Click the ̶0;Tools̶1; option again, then select the ̶0;Weld̶1; option and click the ̶0;Anchor̶1; option. Select another brick and place it into the top corner of the doorway. Once you place the brick up, it will anchor itself in position.
Click the ̶0;Tools̶1; option again, then select the ̶0;Weld̶1; option and click the ̶0;Anchor̶1; option. Select another brick and place it at the bottom of the doorway.
Click the ̶0;Modify̶1; option in the top menu, then drag the top corner of the doorway brick until it runs the full length of the doorway. Click the top corner of the brick again to reduce the height of the brick until it is barely visible.
Click the ̶0;Select̶1; and the Weld̶1; options in the menu, then click the door you are going to use and place it onto the anchor blocks. The door will lock onto the Anchor blocks that you made. The door will only be able to swing one way because of the doorway blocker brick.