Basics

Design

One of the criticism of French Cleats are that one can bump containers etc off of them
This can be solved via Screws for permanent fixtures
For Modular "Quick Swappable" designs, one can insert a "key" to have it's top be supported by the above cleat
Designs for this method:
- A Video by the YouTube Channel "Craftswright" Titled "Watch This Before Building A French Cleat Wall!" ( ~13 Minute Watch )(A Square Key that Fills the Above Gap)
  - Disadvantage is that it requires blank space on at least one side to allow removal of the key
- A Video by the YouTube Channel "Craftswright" Titled "The REAL Key to Locking French Cleats?" ( ~5 Minute Watch )

A Video by the YouTube Channel "A Glimpse Inside" "This FRENCH CLEAT Design Change is AWESOME" ( ~12 Minute Watch )
- They essentially but the same bevel on top of the attachments cleat so you can make stacks that you can take with you as a mobile cabinet of sorts around the shop

The Wikipedia Page on French Cleats
A Video by the YouTube Channel "The Honest Carpenter" Titled "FRENCH CLEATS EXPLAINED...In 5 Minutes!" (~5 Minute Watchtime ) (Good Basic Summary)
A Video by the YouTube Channel "Popular Woodworking" Titled "How to Make French Cleats | Tricks of the Trade"
A Video by the YouTube Channel "Stumpy Nubs" Titled "How a French cleat changed everything!" (Essentially on how not only can they be used for modular storage, but also for attaching permanent things like Cabinets or Shelves to the wall in a level manner easily. You can level and attach the french cleat, which is very light, then carry the heavy assembly and place that on the french cleat without needing to worry about leveling it.)