Set meta/command/⌘ key as Launchpad shortcut?
To make this work you have to use a third party tool: Karabiner.

In the customized keycode below I assume that you haven't enabled the consumer key function in System Preferences but have to access the consumer keys by using the fn+F1...F12.

In the example below just the left command key launches Launchpad if hit once. A second hit will close Launchpad again.

You can use either the left or the right command key as usual otherwise (e.g. open files with cmd+O or print cmd+P)


Download, install and open Karabiner
Open in the menulet Karabiner -> Preferences
Open the tab Misc &amp; Uninstall
Hit the button Open private.xml
Open the file private.xml with an appropriate editor
Enter the customized keycode

&lt;?xml version="1.0"?&gt;
&lt;root&gt;
    &lt;item&gt;
        &lt;name&gt;When you type Command_L only, start Launchpad&lt;/name&gt;
        &lt;appendix&gt;(Change Command_L lazy start Launchpad)&lt;/appendix&gt;
        &lt;identifier&gt;remap.command_l_lazy_to_launchpad&lt;/identifier&gt;
        &lt;autogen&gt;__KeyOverlaidModifier__ KeyCode::COMMAND_L, KeyCode::VK_LAZY_COMMAND_L, KeyCode::LAUNCHPAD, ModifierFlag::FN&lt;/autogen&gt;
    &lt;/item&gt;
&lt;/root&gt;

Save the file
Open in the menulet Karabiner -> Preferences the tab Change Key
Hit the ReloadXML button
Enable the remapping. It should be listed at the beginning.