TextMate 2 Bundle creation
As of this writing, the beginning steps are:


Go to Bundles (menu) > Edit Bundles…
Press ⌘N to create a new bundle.
The bundle gets saved in ~/Library/Application\ Support/Avian/Bundles; you may wish to right-click on the saved bundle and choose Show Package Contents to see what's inside your bundle.


Further info can be found e.g. here and here.