Tutorials on my YouTube: https://youtu.be/YIGILTr5e2I
Installation is very simple, just download the zip file (no need to unzip) and install it in Blender under preferences>addons>install.
After installing you will see this preferences window. The addon is plug-and-play, but if you want to save your own materials to the favourites list you can select a path for InstaMat to save them to. There are also options for changing what InstaMats are mapped to what buttons and a button for hiding the Smudgr Pro panel if you don't own my other addon.
Addon panels and menus
Pressing Shift+F opens the InstaMat pie menu:
Changing the main menu
If you don't like the classic pie menu, for example because it will select options even when you click far away from them, there is another menu option available: By pressing the button on the right bottom you can change between full pie menu and a list based pie menu. The list based menu is enabled by default.
Operators (Main Menu)
The grey colored buttons in the main menu are operators. Hover over them to see what they do. When clicked in the main menu, they will perform their action and automatically close the pie menu.
InstaMat Buttons (Main Menu):
The buttons on the left open a new popup window for creating a new InstaMat material. The pie menu automatically closes when selecting one of these. You can undo the adding of an InstaMat with Ctrl+Z. After selecting the options in the InstaMat popup panel, you can still find the options for changing the material in the QuickAdjust panel (see below)
The dark colored menus with the arrow on the side open as 'Panels'. These show different options, and they do not close automatically when you click buttons.
These are panels that pop up when running certain operators, like 'Add InstaMat', 'Randomize HSV' and 'Find Similar Materials. Pressing buttons inside these panels does not close them, except the OK button on the bottom.
The menus are the three ('most used', 'favourite' and 'all instamats') buttons on the right bottom of the main menu. These open on the side showing a material list. Clicking anything inside these menu's will close the pie menu.
Favourites Library panel:
There is one more panel besides the pie menu, that is the library panel. This panel, found under your materials tab, allows you to add and remove materials from your favourites. These favourites will show up in the 'Favourite' menu shown above