The other day, I finally got fed up with the pile of random items that litter my desk. I also needed a place to mount a monitor for the occasional software project, but didn't want the constant temptation of a permanently mounted television. A french cleat seemed to be the most modular approach I could take given the offcuts I already had in my shop.

Supplies

Saw (table or circular)
1/4" dowels
Drill set
Wood glue
Clamps
Nice looking offcuts

Step 1: Decide on Your Offcut and Cut Your French Cleat

I ended up using an 7" wide piece of walnut at 22" long, but any piece of hardwood will do. Set your table saw (or circular saw angle setting) to 45º and cut the piece lengthwise at a width that looks good to you. I my case, I cut the wall mounted piece at 4" and the hanging portion at 3".

Step 2: Cut/assemble the Pieces for Your Letter Box

I included the Fusion 360 and sketchup files for this project, but use these as a guide given your own offcuts. This letter box was only the first modular hanger for this french cleat, but you could imagine how shelves, drawers, or tool racks would work well in this configuration.

Step 3: Attach Your Cleat Hanger and Hang

The only thing left to do is fasten the cleat hangers to the back of your letter box (with wood screws) and hang them on the wall. A couple important details here:

Make sure your drywall screws are rated for the weight they'll be carrying (with some headroom)
Triple check that your cleat hangers are level when attached. No one likes a crooked cleat.

Step 4: Build More Hangers!

An organization system perfectly suited to your needs can be super satisfying (especially when you built it yourself). Add a shelf, a tool rack, maybe a dart board? Expand the system to clean up your desk and perfectly fit your needs.