Mortise and Tenon add-in creates a mortise and tenon joint between two boards. This add-in allows you to specify the dimensions and location of the joint. It is particularly useful in woodworking.

Steps:

1. Press the "Mortise and Tenon" button in the "Modify" panel.
2. Select a board to cut the mortise.
3. Select a face for the tenon.
4. Specify joint depth, length, thickness, offsets, and number of tenons.
5. Press the "OK" button.

Help online: https://maciejrogowski.com/mortise-and-tenon-help/

Install:

1. Download the installer from Autodesk App Store.

2. Right-click on the "Downloads" folder and choose "Open in Finder".

3. Right-click on the "MortiseAndTenon_macos.pkg" -> "Open With" -> "Installer". 

Uninstall:

You can unload the add-in without uninstalling it by clicking the "Stop" button when the add-in is selected in the list box on the "Add-Ins" tab of the "Scripts and Add-Ins" dialog.

Unchecking "Run on Startup" causes the add-in not to be loaded in future sessions of Autodesk® Fusion 360™.

- Navigate to ./ApplicationsPlugins folder and select the app bundle you want to uninstall

- Either drag the app bundle to the Trash or right-click and select “Move to Trash”

- Right-click on the Trash-Can and select “Empty Trash”

- If you prefer keystrokes, you can also just select the app bundle and then hit Command+Delete to move the app to Trash, then empty the Trash and the app will be removed.